https://orcid.org/0000-0003-0856-6474
Abstract
Previous research has highlighted the prominent behavior of lone wolf terrorists to produce and share a manifesto publicly, outlining their frustrations and motivations for their eventual terrorist attack. This article aims to explore this phenomenon, focusing on the timelapse between when a terrorist manifesto is posted online and when the eventual attack occurs, discussing the time difference between the two events for 12 cases of lone wolf terrorism. The results revealed that the average time lapse between when a manifesto was posted online and when the terrorist attack occurs is one hour, 43 min. Limitations and implications are discussed in detail.
Lone wolf terrorism is a phenomenon which has become steadily more prominent throughout the modern terrorism era, with there being a growth in the phenomenon of 143% between the years of 1970 and the early 2000’s,Footnote1 with this growth continuing up to the late 2010s and predicted to continue increasing indefinitely.Footnote2 Individuals acting out terrorist activity independently is not a new phenomenon, with some of the most notable and deadly instances of terrorism throughout history being carried out by a lone actor, from the wall street bombing in 1920Footnote3 to the Christchurch Mosque shooting in 2019.Footnote4 However, with evidence to suggest that this phenomenon has dramatically increased in recent years, with a further raise of incidence of 70% in the years between 2014 to 2018 alone, investigating these instances of lone wolf terrorism to explore and enhance current methods of investigative practice are more essential than ever.Footnote5
There are numerous arguments as to why the phenomena of lone wolf terrorism may be increasing, one of which could be the ever-rising presence of the internet and social media in our daily lives.Footnote6 Although the internet has provided the world with a wide range of useful and practical applications to make modern life easier, such as global communication and information retrieval, it has been argued that these advancements have also enhanced the efforts and frequency of radicalization.Footnote7 The internet has provided a space for extreme opinion and ideologies to be presented to large audiences freely, while also allowing followers of these ideologies to congregate in one space virtually to discuss and promote their ideology further to other users who may not have necessarily encountered these extreme opinions directly outside of the cyberspace.Footnote8
The internet, with an added focus on social media, has provided terrorist and extremist groups a valuable tool that can be utilized to promote their groups ideology and not only encourage the radicalization process but also recruitment for their group.Footnote9 With online social platforms providing extreme groups with the means to present their ideology and propaganda to large audiences as frequently as they want, it has been showcased in research how social media users are being exposed to extreme narratives and content frequently during their time on social media.Footnote10 This frequent exposure to extreme ideology can then potentially lead to an individual becoming radicalized and adopting the extreme ideas and notions they are being exposed to online.Footnote11 However, the influence and inclusion of social media and the internet is not only a phenomenon involved with group radicalization but there is evidence to suggest that the internet has become a prominent instigator and facilitator for the lone wolf radicalization process, allowing individuals to become familiar and indulge with extreme opinions and ideologies from the comfort of their own home.Footnote12 With the internet and social media providing these individuals with all the information they need regarding the extreme notions and narratives, they are able to adopt these newfound ideologies without receiving any interaction from other likeminded individuals or any of the groups that are promoting this content online. This independence from other individuals is also present in later stages of the radicalization process, where research suggests that the internet has made the process of preparing for an attack easier and harder to detect, such as the surveying of a potential target area and the gaining of materials and weapons used for the attack.Footnote13 If the individual can become radicalized to extreme ideologies and can prepare and survey potential targets via the internet and without interaction with others, as opposed to conducting these actions offline and depending on other individual, this provides less signposts for intervention to their intent and potential violent plan for promoting their newfound extreme ideology
As lone wolf terrorism operates differently to group terrorism, in regard to the independence of the individuals involved, there is a distinction between individuals who commit acts of terrorism and are associated with a group, who work with other members of that organization to plan and commit the attack, and lone wolf terrorism, which is defined by SimonFootnote14 as:
…the use or threat of violence or nonviolent sabotage, including cyber-attacks, against government, society, business, the military (when the military is not an occupying force or involved in a war, insurgency, or state of hostilities), or any other target, by an individual acting alone or with minimal support from one or two other people (but not including actions during popular uprisings, riots, or violent protests), to further a political, social, religious, financial, or other related goals, or, when not having such an object, nevertheless has the same effect, or potential effect, upon government, society, business, or the military in terms of creating fear and/or disrupting daily life and/or causing government, society, business, or the military to react with heightened security and/or other responses.
Research exploring why individuals perform lone wolf attacks as opposed to working with a group, has produced numerous assertions, one of which being that although lone wolf individuals are often incredibly devoted to the group ideology and willing to participate in any extreme action the group are planning, the extremist groups avoid the use of opting for a lone wolf operative as they are more prone to failure.Footnote16 This increase in potential failure is not necessarily a failure of attack but a failure in sending as big of a message as possible without simultaneously damaging their reputation and undermining public support, often some of the main motivations for a terrorist attack.Footnote17 There is also the notion that these eventual lone wolf terrorists are potentially viewed as too “extreme” from other supporters of the same ideology, with many lone wolfs initially being a member of an extremist organization, only to leave or be excommunicated due to disagreeing with the group’s methods or agenda.Footnote18 Another argument for these radicalized individuals opting to operate as independently as possible, is the fear of detection and their plans being exposed due to be under increased scrutiny and suspicion due to affiliation with an extreme ideology.Footnote19 This potential decrease in suspicion is highlighted in the case study of Omar Mateen who committed a lone act of terrorism resulting in the deaths of 49 people, where it is argued that his attack was more successful due to him not being placed under any suspicion when purchasing his attack weapons due to any previous contact and affiliation with a dangerous extreme group.Footnote20 It is this element of reduced signposting and identity markers compared to other potential terrorists who have identified links with an extreme organization, that make lone wolf terrorists difficult to track, as they produce little evidence to their intentions in the lead up to the eventual attack.Footnote21
However, one probable signpost that potential lone wolf attackers may provide, is their personal manifestos that they share before the planned attack.Footnote22 A terrorist’s or extremist’s manifesto is broadly defined as a communication from the attacker prior to the attack, that states their ideology and motivation behind the crime they are yet to commit, often containing their perspective on the problems and issues that have influenced them to take action on their self-justified target.Footnote23 Manifestos often act as the authors public statement of intent where they promote their justifications for committing their eventual attackFootnote24 often with the intention to encourage other individuals with likeminded ideologies to follow in their footsteps and take further action to promote the cause highlighted in the manifesto.Footnote25
Research has highlighted the escalating tendency for lone wolf terrorists to produce and share a manifesto before they commit the attack, with this behavior being ever more prevalent amongst assailants who adopt extreme far right ideologies.Footnote26 It could also be theorized that producing and sharing a manifesto may be a more prevalent behavior of lone wolf terrorists due to their absence of affiliation with an extremist group which, without an encompassing manifesto of their beliefs and motivations, might result in their attack aim and intention being misinterpreted, diminishing the overall purpose of the attack which is often to inspire others to take similar action.Footnote27 If no one outside the preparation and implementation of the event is aware of the motivation and purpose for the attack, as is often the case with lone wolf attacks,Footnote28 then the cause the individual is committing the attack for is not being promoted or forwarded. This makes a public declaration of intent in the form of a manifesto imperative for lone wolf attackers, especially if they intend to encourage and inspire others to carry out similar actions.Footnote29 This increase in producing manifestos before committing an act of terrorismFootnote30 could be instigated by two factors, potentially simultaneously: A general rise in terrorism and the ease of communication the internet provides.Footnote31 The internet provides a valuable canvas for a potential terrorist to paint their version of the preceding events and ideological motivation that has led them to the point of carrying out radical action and present this perspective to a global audience with little effort, in the hopes of gaining a supportive following.Footnote32
The internet has provided these individuals with the means to dictate when and where their manifesto is shared, even dictating how it is presented and even potentially to who, as they have the option to share their manifesto privately to their followers or send directly to individuals via email. With lone attackers having the means to dictate who and when people see their ideological intentions, this potentially opens up an avenue of investigation in regard to the behavior and psychology of a lone wolf attacker, as making the change from keeping their extreme ideology private to making their intentions and beliefs public may indicate a behavioral escalation and potentially a further step forward toward committing an ideologically motivated act of violence. Although the internet has potentially enhanced the ease at which a potential terrorist can operate and share their ideologies, the posting of their manifestos on the internet has provided investigators not only with a digital footprint of the individual but has simultaneously provided researchers with an avenue of exploration regarding the timeline of a lone wolf terrorist.
Aim
With the potentially valuable feature of the internet in the journey of a lone wolf terrorist preparing to commit an act of terrorism, research has indicated that lone wolfs “leak” their future extremist intentions before they eventually carry out the attack.Footnote33 This “Leakage,” explained by Meloy and O’TooleFootnote34 as “the communication to a third party of an intent to do harm to a target,” is a prevalent phenomenon that is often present in contemporary threat assessment research that explores violence that involves premeditation.Footnote35 Research has highlighted that this leakage warning behavior can take the form of statements to friends and family36 37 but can also prominently take the form of a violent targeted manifesto toward the intended target of the planned attack.Footnote38 Furthermore, research has showcased how lone wolf attackers are more likely to share their convictions through pre-event leakage.Footnote39 The main problem counter terrorism agencies and law enforcement forces have is identifying these signposts/leakages and gauging their significance, as not every potential signpost or red flag of terrorist intent is justified or valid. However, if producing and sharing a manifesto is a prominent feature of lone wolf terrorism, then exploring the timings of when eventual lone wolf terrorists share their manifesto and determining where this public sharing of their ideology and intentions fits into the timeline of a lone wolf attack might provide valuable inferences for detection and investigation. A productive step in this investigative direction would be to first establish the time differences between when a manifesto is shared/posted online and when the attack occurs, using previous lone wolf attacks. The present study aims the aforementioned.
Method
Cases
All the cases selected adhered to an exclusion criterion that was fitting to the exploration (Online manifestos of lone wolf terrorists) while also ensuring that all cases were measured and compared on the same values (e.g. time the manifesto was posted). Therefore, the following exclusion criteria were applied when collecting the relevant data and selecting which cases to incorporate:
Exclusion Criteria
Attacks where the perpetrator did not post a manifesto.
Attacks were committed by more than one individual.
Attacks where the perpetrators manifesto did not have a digital footprint/was not posted online (e.g., Jim David Adkisson).
Attacks where, although the perpetrators posted their manifesto online, the information about the manifesto’s timestamps are not available via public online domain platforms (adhering to the ethical requirements of this research).
This resulted in a final sample size of 12 cases being selected for this research, with all adhering to the requirements for this exploration.
Data Sources
The information sourced for this research was collected from online public domains, reputable newspapers and news organizations who reported on the attacks. The timestamps collected and utilized, were cross referenced across sources to ensure accuracy of the reports. Furthermore, because this project explored only manifestos published online, the attacks selected were all orchestrated within a 16-year window, with the oldest case in the sample taking place in 2006. The cases selected are outlined in below.
Table 1. Examined lone wolf cases.
Analysis
The aim of the analysis was to compare the individual time differences between an individual posting their manifesto online and the time of their lone wolf attack with the other time differences in the data set to establish an average approximate time of suspension between manifesto posting and attack implementing.
Results
It is in important to note that for the descriptive of the individual events (posting and attack: ), the times presented are formatted as they were in the data collection: Time of day (e.g. Mean average of 14:16 represents the average time a manifesto was posted was 2:36pm). Therefore, the descriptions of these particular variables may not hold much interference value besides providing a potentially interesting avenue of investigation.
Table 2. Table to show the descriptive statistics of the attack variables.
However, the descriptive values for the combined variables on a case-by-case basis do provide valuable results (). The skewness for this variable was positive and very large (2.19), therefore the appropriate central tendency to adopt and present was the median and Interquartile range (IQR). As seen in the table below, the results reveal that the median average time between when a perpetrator posted their manifesto online and when they committed the attack was 1 h and 43 min.
Table 3. Table to show the descriptive statistics of the compared variables.
Discussion
The results revealed that the average time span between when a lone wolf terrorist shares their manifesto with others online and when they commit the attack is one hour and 43 min. All the cases varied in their attack characteristics and motivations, yet the results potentially indicate that the assailants all shared the notion that their manifesto should be shared as a potential last step before committing the attack. One of the cases, Joseph Stack III, was found to be an outlier compared to the other cases, due to the subjectively longwinded timelapse between when the manifesto was posted and the attack occurring (10 h 14 min).
This could indicate that although the other cases recorded much shorter timelapses, averaging one hour 43 min, there are instances of lone wolfs taking substantially longer to commit their attack. This is a valuable assumption, however, in the case of Joseph Stack III his attack involved other variables that other cases did not, such as in the hours between the post and the attack he set fire to his house and drove over 20 miles to his rented airplane hangar to retrieve the plane he would eventually use in the attack.Footnote40 In the other cases, the assailants were possibly either already set up to commit the attack or they shared their manifesto when near or on the way to the target, highlighting how the internet has potentially enhanced the ease and process of sharing one’s manifesto. This could also suggest that the posting of a manifesto is last thing the assailant does before physically preparing for the attack (e.g. traveling to the target).
Regardless, the results of this research potentially highlight a disconcerting feature of lone wolf terrorism, that the sharing of a manifesto is one the final stages of the preparation for an attack. Previous literature that has explored this topic has potentially produced reasoning for this short time lapse between the sharing of the post and the attack occurring, as research exploring the language of manifestos showcases how the narrative through these works become more directed toward advocating and preparing for violence as the manifesto narrative progresses.Footnote41 If manifestos are a snowballing narrative that becomes more directed toward violent action, then this could suggest that the sharing of the manifesto could be a sign that the author has reached the conclusion that action is the only way to ensure their ideological change, also potentially explaining the short time lapse between their manifesto’s conclusion and their attack.
This notion also corresponds with the “bathtub” model of radicalization,Footnote42 which suggests that the decision-making process of lone actors to execute an act of terrorism acts the same way as a vessel with numerous faucets of influence (e.g. Ideological beliefs, personal situation), adding varying amounts of metaphorical water to the overall motivation/“bathtub” of the individual, where once the threshold of the bathtub has been reached the individual will then execute their terrorist intention. If manifestos are acting as a running narrative of the individuals’ beliefs, the directional change to more violent means could be a signpost for their “bathtub” filling up, with the decision to conclude and share their manifesto being a signpost that they have reached this pressurized threshold. If the timelapse between the sharing of a manifesto and the terrorist attack is small, this could potentially suggest that the individual’s radicalization threshold may have been reached and documented in the final statements of the manifesto. This would support the notion that the sharing of a manifesto is a valid signpost for a potential lone wolf attack or at the very least an individual who has become fully radicalized. Additionally, the “Ladder of identity construction” produced by Berger,Footnote43 which provides a visual evolution of the process an individual undergoes during radicalization, further showcases the notion that producing a manifesto and revealing leakage of violent intent could indicate an individual it at the latter stages of the radicalization process, as Berger highlights how warning others of the apocalyptic threat that the targeted group threatens society is a later stage signpost of the radicalization process. In the context of Berger’s model, the individual releasing their manifesto publicly could indicate that the individual has accepted that the outgroups threat is critical and that the possible solutions to resolve this threat have reduced, with nonviolent actions no longer being acceptable or available for the size of the threat. Looking at the two models simultaneously (“ladder of identity construction” and “bathtub model”), both models potentially indicate the valuable inference that the posting of a manifesto can indicate in regard to the stage of radicalization the author of the manifesto is at, with both models potentially suggesting that this leakage might be a signpost that the individual is in the very latter stages of the radicalization process and is close to committing an act of violence.
Currently, an individual posting an extremist manifesto online is not grounds for a search warrant and even if they were, the Law Commission highlighted that in the UK there is an inefficiency in the granting of search warrants, with some police forces having to sometimes wait three weeks to obtain a warrant.Footnote44 In the US, the time is substantially shorter with the grant of a search warrant often only taking a few hours once enough evidence has been presented to the relevant authorities.Footnote45 In the US, a lot of behaviors that could constitute potential leakage of violent intent (posting extreme narratives online and sharing malevolent intent to harm) are not against the law and are often protected by the laws and constitution surrounding free speech.Footnote46 Additionally, with the high cost of deploying surveillance and search resources often being prioritized to cases with more substantial evidence, incidents where the only evidence is a potential online declaration of violent intent are often not labeled as high priority.Footnote47 Yet, law enforcement agencies like the FBI have released statements urging civilians to report any information on potential extremist activity, including brief sightings of concerning behavior, as they claim that their investigations into preventing premediated attacks of violence are enhanced through the early recognition and reporting of leakage behaviors by these potentially radicalized individuals.Footnote48 However, as suggested by the results of this research, even if an online declaration of extremist violence was enough grounds to be granted a search warrant that is received in hours or if an individual reported to authorities any leakage behavior they witnessed that could indicate a potential violent attack, this still may not be enough time to prevent an eventual attack if the average time lapse is one hour 43 min between a prominent leakage behavior such as releasing a manifesto publicly online. Not only that, but the manifestos posted by these lone wolf assailants are often either anonymous and/or only known to the police after the attack has already occurred and they are looking into the perpetrator’s timeline and motivations. So, although manifestos might provide a valuable signpost for eventual terrorist activity, the aggravating factors that if they are discovered prior to the attack, they are either anonymous or do not permit enough for a search warrant, as well as the small timelapse between the post and the attack, makes use of this inference in a practical investigation challenging. However, the indication from this research that there may be a potentially prominent signpost of an increasingly growing and elusive phenomena promotes the need for further exploration not only on where a manifesto fits in with a potential terrorist’s preparation for an attack but also practical innovations of utilizing this information for the enhancement of counter terrorism interventions.
Implications
One potential innovation and implication that could be produced from the research in this area is the promotion of reporting any documents and/or statements that have the appearance of an extremist manifesto. However, this already provides a problem as manifestos vary not only in appearance but in their language and where they are posted. Yet, there has been prominent research in the field that has showcased that there are potentially identifiable themes and commonalities that the manifestos of individuals who go on to commit an act of terrorism seem to utilize.Footnote49 This potentially provides a valuable addition to the current research findings, combining both the potential profile of a terrorist manifesto and the urgency in the time to act, that future research could explore even further. Another research avenue that could be explored is the threshold of evidence required for police action to occur. As highlighted previously, lone wolf terrorists are particularly elusive due to the limited signposts and indications they provide of their intentions leading up to the event.Footnote50
If manifestos are to be utilized as a valuable signpost for potential terrorist activity, there would need to be either a lowering in the standard/volume of evidence required for an investigation to take place or an introduction of new policy regarding potentially radicalized individuals. This would also require the detection of these manifestos to occur as soon as possible, as this research showcased the potentially small timeframe between the manifesto being made public and violent action being taken. Further research should explore the potential for software and online algorithms to aid in the policing of documents and statements online that may indicate intended terrorist activity. Current efforts to utilize technology as a screening process for extremist content has produced mixed results, with research even highlighting that prominent social media sites with large and expensive safeguarding procedures failing to prevent extremist content from being prevalent on their sites.Footnote51 As shown in details of the cases highlighted in this research (see ), manifestos often don’t appear or originate from popular online sites, highlighting further the potential urgency for an intervention that can aid in the monitoring and detection of extremist manifestos online.
Limitations
A limitation of this research is the potential risk of inaccuracy regarding the timings of the case attacks. Although all times were cross referenced and compared with numerous sources to ensure the highest accuracy, as information comes from public sources such as news organizations and not official reports of the cases, there may be potential for slight inaccuracies with the time frames utilized for this research. Another potential limitation of this research is the sample size, which only included 12 cases of lone wolf terrorism. However, this perceptibly small number of cases is due to a combination of the sparse nature of the phenomena and the intricate details of the case (e.g. timestamps) and the strict exclusion criteria the research adhered to.
Despite this, research that has explored lone wolf terrorism has also utilized seemingly low sample sizes, with Hamm and SpaajFootnote52 collating in their research a combination of 98 lone wolf attacks between the years 1940 and 2013, with only 45 authentic lone wolf cases occurring post 9/11. The current research explored similar cases, with the addition of the offender posting their manifesto online, adding the unwritten circumstance that the included cases must have occurred post-internet, reducing this sparse population even further. Compared to the full population of lone wolf terrorist cases, the current studies sample size is not as small as this sample size would be exploring other research areas.
There was also the limitation of using a parametric test (paired samples t-test) when the data was reportedly skewed, which potentially limited the validity of the results. The sample size was also small, impacting the overall power of the test and its results. However, the nature of the data justified the use of this analysis, as the data utilized for analysis was classified as the time the event occurred regarding its placement in the time of day on a standard analogue time system (e.g. Time of post: 14:00, time of attack: 14:30). This data classification was naturally going to produce skewed data as all the events did not start at an absolute zero starting point and occurred independently from each at differing points in the day on separate dates. Also, as mentioned in the results section directly, the average values of the time the manifesto was posted and the attack occurring, provide little inference due to this classification. Future research may look to mitigate these limitations to provide stronger inferences in this area.
Conclusion
Lone wolf terrorism is a an increasingly prominent phenomena which has demonstrated its elusive nature through the difficulties the phenomenon presents counter terrorism efforts. However, although assailants who engage in lone wolf terrorism often present few signposts and warnings of their intentions before their eventual attack, the sharing of their personal manifestos has provided a potential window for researchers to peer through and understand the phenomena further. This research provided potentially valuable information on the significance of manifestos in the timeline of lone wolf terrorism, suggesting that the posting of an extremist manifesto might be an indication of violent action to occur shortly after. However, without delving further into the manifestos and the themes included within them, it is impossible to provide inference on the mental state of these assailants and if the posting of these manifestos is significant to them in their final preparation for an act of violence. If the sharing of a manifesto is an important final step in the process of committing a lone wolf terrorist attack, then research investigating enhanced methods of detecting when a manifesto has been shared and attempting to further understand the breadcrumbs leading up to when a manifesto might be shared could provide useful inferences for counterterrorism agencies in their seemingly impossible pursuit of the elusive lone wolf terrorist typology.
Disclosure Statement
No potential conflict of interest was reported by the authors.
Notes
1 Ramon Spaaij, Understanding Lone Wolf Terrorism: Global Patterns, Motivations, and Prevention (Berlin: Springer, 2012).
2 Martin Joseph Gallagher, “Lone Wolf Terrorists: Examining Motives and Methods of Stand-Alone Terrorists,” in Books on Google Play Indoctrination to Hate: Recruitment Techniques of Hate Groups and How to Stop Them, ed. Edward Dunbar (Santa Barbara, CA: ABC-CLIO, 2022), 128–44.
3 Jeff Glor, “New York’s Worst Terror Attack before 9/11 was 100 Years Ago. No One Was Ever Convicted,” History, 12 September 2020, https://www.cbsnews.com/news/wall-street-bombing-new-york-terror-attack/.
4 Wale Azeez, “YouTube: We’re Learnt Lessons From Christchurch Massacre Video,” Yahoo Finance UK, 15 May 2019. https://uk.finance.yahoo.com/news/you-tube-weve-learnt-lessons-from-christchurch-ma ssacre-video-163653027.html.
5 “The Rise of the Self-Radicalised Lone Wolf Terrorist,” Vison of Humanity, https://www.visionofhumanity.org/increase-in-self-radicalized-lone-wolf-attackers/(accessed 1 October 2022.
6 Catherine Appleton, “Lone Wolf Terrorism in Norway,” The International Journal of Human Rights 18, no. 2 (2014): 127–42. https://doi.org/10.1080/13642987.2014.889390.
7 Maura Conway, “Determining the Role of the Internet in Violent Extremism and Terrorism: Six Suggestions for Progressing Research,” Studies in Conflict & Terrorism 40, no. 1 (2017): 77–98. https://doi.org/10.1080/1057610X.2016.1157408.
8 Dana Janbek and Valerie Williams, “The Role of the Internet Post-9/11 in Terrorism and Counterterrorism,” The Brown Journal of World Affairs 20, no. 2 (2014): 297–308. https://www.jstor.org/stable/24590989.
9 Thomas James Vaughan Williams and Calli Tzani, “How Does Language Influence the Radicalisation Process? A Systematic Review of Research Exploring Online Extremist Communication and Discussion,” Behavioral Sciences of Terrorism and Political Aggression 1, no. 1 (2022): 1–21. https://doi.org/10.1080/19434472.2022.2104910.
10 Thomas James Vaughan Williams, Calli Tzani, Helen Gavin, and Maria Ioannou, “Policy vs Reality: Comparing the Policies of Social Media Sites and Users’ Experiences, in the Context of Exposure to Extremist Content,” Behavioral Sciences of Terrorism and Political Aggression 1, no. 1 (2023): 1–18. https://doi.org/10.1080/19434472.2023.2195466
11 Michael Wolfowicz, Badi Hasisi, and David Weisburd., “What are the Effects of Different Elements of Media on Radicalization Outcomes? A Systematic Review,” Campbell Systematic Reviews 18, no. 2 (2022): 1–50. https://doi.org/10.1002/cl2.1244
12 Tomas Zeman, Jan Bren, and Rudolf Urban. “Role of Internet In Lone Wolf Terrorism,” Journal of Security and Sustainability Issues 7, no. 2, (2017): 185–92. https://jssidoi.org/jssi/uploads/papers/26/Zeman_Role_of_Internet_in_Lone_Wolf_Terrorism.pdf.
13 Zeman, Bren and Urban, ‘Role of Internet in Lone Wolf Terrorism’
14 Jeffery Simon, Lone Wolf Terrorism: Understanding the Growing Threat (New York: Prometheus Books, 2013), 266.
15 Ramon Spaaij and Mark Hamm, “Key Issues and Research Agendas in Lone Wolf Terrorism,” Studies in Conflict & Terrorism 38, no. 3 (2015): 167–78. https://doi.org/10.1080/1057610X.2014.986979.
16 Daniel Byman, “How to Hunt a Lone Wolf: Countering Terrorists Who Act on Their Own,” Brookings, 14 February 2017, https://www.brookings.edu/opinions/how-to-hunt-a-lone-wolf-countering-terrorists-who-act-on-their-own/.
17 Sara Polo and Kristian Skrede Gleditsch. “Twisting Arms and Sending Messages: Terrorist Tactics in Civil War,” Journal of Peace Research 53, no. 6 (2016): 815–29. https://doi.org/10.1177/002234331666799.
18 Edwin Bakker and Beatrice de Graaf, “Lone Wolves: How to Prevent This Phenomenon?” Terrorism and Counter-Terrorism Studies 1, no. 2 (2010): 1–8. https://doi.org/10.19165/2010.2.01.
19 Mathew Harwood, “The Lone-Wolf Terror Trap: Why the Cure Will Be Worse Than the Disease,” Last modified 5 February 2015 on American Civil Liberties Union. https://www.aclu.org/news/national-security/lone-wolf-terror-trap-why-cure-will-be-worse-disease.
20 Adeline Toevs, “Analyzing Threat: Organized Extremist Groups vs. Lone Wolf Terrorists in the Context of Islamist Extremism,” The Commons: Puget Sound Journal of Politics 1, no. 1 (2020): 1–10. https://soundideas.pugetsound.edu/cgi/viewcontent.cgi?article=1011&context=thecommons.
21 Byman, “How to Hunt a Lone Wolf”
22 Zeman, Bren and Urban. “Role of Internet in Lone Wolf Terrorism,” 185–92.
23 Kosta Lucas and Daniel Baldino. “White Knights, Black Armour, Digital Worlds: Exploring the Efficacy of Analysing Online Manifestos of Terrorist Actors in the Counter Terrorism Landscape,” in Counter-Terrorism, Ethics and Technology, ed. Adam Henschke, Alastair Reed, Scott Robbins, and Seumas Miller (Springer, 2021), 199–221.
24 Sophie Kaldor, “Far-Right Violent Extremism as a Failure of Status: Extremist Manifestos through the Lens of Ressentiment,” The International Center for Counter-Terrorism 1, no. 1 (2021): 1–33. https://doi.org/10.19165/2021.1.05
25 Jacob Ware, “Testament to Murder: The Violent Far-Right’s Increasing Use of Terrorist Manifestos” (International Center for Counter-Terrorism, 2020).
26 Ware, “Testament to Murder,”
27 J.M Berger, “The Dangerous Spread of Extremist Manifestos,” The Atlantic, 26 February, 2019, https://www.theatlantic.com/ideas/archive/2019/02/christopher-hasson-was-inspired-breivik-manifesto/583567/.
28 Simon, “Lone Wolf Terrorism,”
29 Lucas and Baldino, “White Knights, Black Armour, Digital Worlds,”
30 Ware, “Testament to Murder,”
31 Appleton, “Lone wolf terrorism in Norway,”
32 Williams and Tzani, “How Does Language Influence Radicalisation,”
33 Zeman, Bren and Urban. “Role of Internet in Lone Wolf Terrorism,” 185–92.
34 Reid Meloy and Mary Ellen O’Toole, “The Concept of Leakage in Threat Assessment,” Behavioral Sciences & the Law 29, no. 4 (2011): 513–27. https://doi.org/10.1002/bsl.986
35 James Silver, John Horgan, and Paul Gill, “Foreshadowing Targeted Violence: Assessing Leakage of Intent by Public Mass Murderers,” Aggression and Violent Behavior 38, no. 1 (2018): 94–100. https://doi.org/10.1016/j.avb.2017.12.002
36 Paul Gill, James Silver, John Horgan, and Emily Corner, “Shooting Alone: The Pre-Attack Experiences and Behaviors of U.S. Solo Mass Murderers,” Journal of Forensic Sciences 62, no. 3, (2016): 710–14. https://doi.org/10.1111/1556-4029.13330
37 Silver, Horgan and Gill, “Foreshadowing Targeted Violence,”
38 Juila Kupper and Reid Meloy, “TRAP-18 Indicators Validated through the Forensic Linguistic Analysis of Targeted Violence Manifestos,” Journal of Threat Assessment and Management 8, no. 4 (2021): 174–99. https://doi.org/10.1037/tam0000165
39 Lasse Lindekilde, Francis O’Connor, and Bart Schuurman. “Radicalization Patterns and Modes of Attack Planning and Preparation among Lone-Actor Terrorists: An Exploratory Analysis,” Behavioral Sciences of Terrorism and Political Aggression 11 no. 2 (2019): 113–33. https://doi.org/10.1080/19434472.2017.1407814
40 Richard Adams, “Joseph Stack’s Suicide Note,” The Guardian, 18 February 2010, https://www.theguardian.com/world/richard-adams-blog/2010/feb/18/austin-irs-joseph-stack.
41 Lars Erik Berntzen and Sveinung Sandberg, “The Collective Nature of Lone Wolf Terrorism: Anders Behring Breivik and the Anti-Islamic Social Movement,” Terrorism and Political Violence 26, no. 5 (2014): 759–79. https://doi.org/10.1080/09546553.2013.767245.
42 Boaz Ganor, “Understanding the Motivations of “Lone Wolf” Terrorists: The “Bathtub” Model,” Perspectives on Terrorism 15, no. 2 (2021): 23–32. https://www.jstor.org/stable/27007294.
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