Fight Crime and Terrorism

Organized crime and terrorism threaten the values of modern democratic societies, as well as the rights and freedoms of citizens, creating a sense of insecurity and undermining public confidence in national authorities. Fighting crime and terrorism encompasses a variety of key areas including (but not limited to) the enhancement of the operational capabilities of law enforcement against organized crime and terrorist threats, the effective information sharing between law enforcement, judicial and intelligence authorities in Europe, the prevention of radicalization, the combat against firearms trafficking, the fight against child sexual exploitation and human trafficking, the digitalization of justice, as well as the cut-off of terrorist financing. Advanced and targeted technologies can help address the challenges of detecting and assessing threats, thus predicting, preventing, investigating and mitigating organized crime- and terrorism-related actions.

M4D develops a number of innovative solutions for improving the capabilities of national and European authorities in their fight against crime and terrorism. In particular, our research and development activities focus on Multimedia Retrieval from various sources including (but not limited to) online resources and sensors, Multimodal Data Fusion, Knowledge Extraction and Reasoning, AI-based Multimodal Analytics including Classification, Clustering, and Social Network Analysis, Computer Vision including Face, Object and Activity Recognition, Visual Analytics to improve situational awareness, and Decision Support to tackle threats in an effective and efficient manner.

The Boston Marathon bombing attack that took place in 2013
Showcases a command & control centre solution utilising AI-based technologies for the protection of similar public events

PROJECTS

PUBLICATIONS

  1. K. Stavrothanasopoulos, K. Gkountakos, K. Ioannidis, T. Tsikrika, S. Vrochidis, I. Kompatsiaris, "CylinDeRS: A Benchmark Visual Dataset for Robust Gas Cylinder Detection and Attribute Classification in Real-World Scenes.", Sensors, vol. 25, no. 4, 2025.
  2. K. Gkountakos, K. Ioannidis, K. Demestichas, S. Vrochidis, I. Kompatsiaris, "A Comprehensive Review of Deep Learning-based Anomaly Detection Methods for Precision Agriculture.", in IEEE Access, vol. 12, pp. 197715-197733, December 2024.
  3. N. Stylianou, T. Tsikrika, S. Vrochidis, I. Kompatsiaris, "Cross-domain Hate Speech Detection for Content Moderation in Greek Social Networks.", in Proceedings of the 23rd IEEE/WIC International Conference on Web Intelligence and Intelligent Agent Technology, Bangkok, Thailand, December 9-12, 2024.
  4. K. Gkountakos, D. Galanopoulos, A. Leventakis, G. Tsionkis, K. Stavrothanasopoulos, K. Ioannidis, S. Vrochidis, V. Mezaris, I. Kompatsiaris, "ITI-CERTH participation in ActEV and AVS Tracks of TRECVID 2024.", in Proceedings of the TRECVID 2024 Workshop, Gaithersburg, MD, USA, November 2024. OPEN ACCESS
  5. G. Koutidis, K. Loumponias, T. Tsikrika, S. Vrochidis, I. Kompatsiaris, "Towards AI-Driven Prediction of Terrorism Risk Based on the Analysis of Localized Web News.", IEEE Access, vol. 12, pp. 167288-167299, 2024. https://doi.org/10.1109/ACCESS.2024.3485913 OPEN ACCESS
  6. E. Patsiouras, S. Kyriakou Vasileiou, S. A. Papadopoulos, N. I. Dourvas, K. Ioannidis, S. Vrochidis, I. Kompatsiaris, "Integrating AI and Computer Vision for Ballistic and Bloodstain Analysis in 3D Digital Forensics.", in Proceedings of the IEEE International Conference on Metrology for eXtended Reality, Artificial Intelligence and Neural Engineering (MetroXRAINE), St Albans, UK, October 21-23, 2024. OPEN ACCESS
  7. E. Villamor Medina, T. Tsikrika, P. Fraternali, L. Caldararu, V. Efstathiou, S. Balbierz, E. Skarlatos, E. Korenjak, A. Karakostas, L. Di Nuovo, F. Benolli, D. Bellingeri, D. Borloo, R. Sciunnach, J. Berggren, O. Manolache, I. Petropoulos, R. Bors, N. Haimov, A. Staniforth, J. Thompson, "PERIVALLON: Improved Intelligence Picture and Operational Capacities to Combat Organised Environmental Crime.", in Paradigms on Technology Development for Security Practitioners, I. Gkotsis, D. Kavallieros, N. Stoianov, S. Vrochidis, D. Diagourtas, B. Akhgar, Eds., Springer, Cham. https://doi.org/10.1007/978-3-031-62083-6_16
  8. N. Avgerinos, P. Mertis, M. Tsagaris, N. Desipris, G. Lyberopoulos, E. Theodoropoulou, K. Filis, J. Sarajlić, M. Pastor, D. Chatzakou, G. Kalpakis, C. Chatzikonstantinou, D. Tsatsou, S. Demertzis, P. Leskovsky, C. Mendes, S. Linehan, J. Mulcahy, I. Karvelas, M. Álvarez Fernández, A. Alegria, "Innovative Digital Forensic and Investigation Tools for Law Enforcement: The EMPOWER & TRACY Approach.", in Proceedings of the 20th International Conference on Artificial Intelligence Applications and Innovations (AIAI 2024), Corfu, Greece, 27-30 June 2024. OPEN ACCESS
  9. S. Bianchi, M. Mancuso, C. Paternoster, G. Kalpakis, T. Tsikrika, S. Vrochidis, D. Kozhuharova, B. Jaeger, "Artificial Intelligence to counter Cyber-Terrorism.",in Proceedings of the International Conference on Cybersecurity and Cybercrime, vol. 10, 5-7 December 2023.
  10. D. Touska, K. Gkountakos, O. Theodosiadou, T. Tsikrika, S. Vrochidis, "Object Detection and Recognition in Visual Content Understanding", CERTH, Thessaloniki, Greece, Tech. Rep. INFINITY project H2020, 2023.
  11. O. Theodosiadou, A. M. Koufakis, T. Tsikrika, S. Vrochidis, I. Kompatsiaris, "Change Point Analysis of Time Series Related to Bitcoin Transactions: Towards the Detection of Illegal Activities.", J. Risk Financial Manag., vol. 16, no. 9, 2023. DOI:doi.org/10.3390/jrfm16090408 OPEN ACCESS
  12. A. Konstantinou, D. Chatzakou, O. Theodosiadou, T. Tsikrika, S. Vrochidis, I. Kompatsiaris, "Trend Detection in Crime-related Time Series with Change Point Detection Methods.", in Proceedings of the CLEF 2023: Experimental IR Meets Multilinguality, Multimodality, and Interaction, A. Arampatzis et al., Eds., Springer, Lecture Notes in Computer Science, vol. 14163, Thessaloniki, Greece, 18–21 September 2023. https://doi.org/10.1007/978-3-031-42448-9_7 OPEN ACCESS
  13. D. Touska, K. Gkountakos, K. Ioannidis, T. Tsikrika, S. Vrochidis, I. Kompatsiaris, "Graph-Based Data Association in Multiple Object Tracking: A Survey.", in Proceedings of the 29th International Conference on Multimedia Modeling (MMM 2023), Bergen, Norway, 9 - 12 January 2023. OPEN ACCESS
  14. O. Theodosiadou, D. Chatzakou, T. Tsikrika, S. Vrochidis, I. Kompatsiaris, "Real-time Threat Assessment based on Hidden Markov Models", Risk Analysis 2023, vol. 43, no. 10, pp. 2069-2081, October 2023. https://doi.org/10.1111/risa.14105
  15. K. Stavrothanasopoulos, K. Gkountakos, K. Ioannidis, T. Tsikrika, S. Vrochidis, I. Kompatsiaris, "Vehicle Color Identification Framework using Pixel-level Color Estimation from Segmentation Masks of Car Parts.", in Proceedings of the Fifth IEEE International Conference on Image Processing, Applications and Systems (IPAS 2022), Genova, Italy, 07-09 December, 2022. OPEN ACCESS
  16. K. Gkountakos, D. Galanopoulos, D. Touska, K. Ioannidis, S. Vrochidis, V. Mezaris, I. Kompatsiaris, "ITI-CERTH participation in ActEV and AVS Tracks of TRECVID 2022.", in Proceedings of the TRECVID 2022 Workshop, Gaithersburg, MD, USA, 6 December 2022. OPEN ACCESS
  17. A. M. Koufakis, T. Tsikrika, S. Vrochidis, I. Kompatsiaris, "M4D-MKLab/ITI-CERTH Participation in TREC Deep Learning Track 2022.", in Proceedings of the Text REtrieval Conference (TREC) 2022 Workshop, Gaithersburg, MD, USA, 14-18 November 2022. OPEN ACCESS
  18. R. Karlović, H. Nitsch, E. Fikenscher, D. Osterman, S. Menexis, T. Tsikrika, S. Vrochidis, I. Kompatsiaris, A. Sahar, "The Threat of Behavioral Radicalization Online: Conceptual Challenges and Technical Solutions Provided by the PROPHETS (Preventing Radicalization Online through the Proliferation of Harmonized ToolkitS) Project.", in Security Technologies and Social Implications: A European Perspective, G. Markarian, R. Karlović, H. Nitsch, and K. Chandramouli, Eds., 2022 (accepted for publication).
  19. G. Begkas, P. Giannakeris, K. Ioannidis, G. Kalpakis, T. Tsikrika, S. Vrochidis, I. Kompatsiaris, "Automatic Visual Recognition of Unexploded Ordnances Using Supervised Deep Learning.", in Proceedings of the International Conference on Multimedia Retrieval, Newark, NJ, USA, June 27-30, 2022, pp. 286-294. DOI: https://doi.org/10.1145/3512527.3531383
  20. K. Pantelidou, D. Chatzakou, T. Tsikrika, S. Vrochidis, I. Kompatsiaris, "Selective Word Substitution for Contextualized Data Augmentation.", in Proceedings of the 27th International Conference on Natural Language & Information Systems (NLDB), Valencia, Spain, 15-17 June 2022, pp.508-516. OPEN ACCESS
  21. P. Kyriakidis, D. Chatzakou, T. Tsikrika, S. Vrochidis, I. Kompatsiaris, "Leveraging Transformer Self Attention Encoder for Crisis Event Detection in Short Texts.", in Proceedings of the 44th European Conference on Information Retrieval (ECIR2022), Stavanger, Norway, April 10–14, 2022, pp. 163-171. DOI: https://doi.org/10.1007/978-3-030-99739-7_19 OPEN ACCESS
  22. K. Gkountakos, D. Galanopoulos, D. Touska, K. Ioannidis, S. Vrochidis, V. Mezaris, I. Kompatsiaris, "ITI-CERTH participation in ActEV and AVS Tracks of TRECVID 2021.", in Proceedings of the TRECVID 2021 Workshop, Gaithersburg, MD, USA (Virtual), 2021. OPEN ACCESS
  23. A. M. Koufakis, T. Tsikrika, S. Vrochidis, I. Kompatsiaris, "M4D-MKLab/ITI-CERTH Participation in TREC Deep Learning Track 2021.",in Proceedings of the Text REtrieval Conference (TREC). OPEN ACCESS
  24. O. Theodosiadou, K. Pantelidou, N. Bastas, D. Chatzakou, T. Tsikrika, S. Vrochidis, I. Kompatsiaris, "Change Point Detection in Terrorism-Related Online Content Using Deep Learning Derived Indicators.",Information, vol. 12, 2021. OPEN ACCESS
  25. K. Gkountakos, D. Touska, K. Ioannidis, T. Tsikrika, S. Vrochidis, I. Kompatsiaris, "Spatio-temporal activity detection and recognition in untrimmed surveillance videos.",in Proceedings of the 2021 International Conference on Multimedia Retrieval, August 2021. OPEN ACCESS
  26. G. Galanakis, X. Zabulis, T. Evdaimon, S.-E. Fikenscher, S. Allertseder, T. Tsikrika, S. Vrochidis, "A Study of 3D Digitisation Modalities for Crime Scene Investigation.", Forensic Sci., vol. 1, no. 2, pp. 56-85, 2021. OPEN ACCESS
  27. C. Iliou, T. Kostoulas, T. Tsikrika, V. Katos, S. Vrochidis, I. Kompatsiaris, "Web Bot Detection Evasion Using Generative Adversarial Networks.", in Proceedings of the 2021 IEEE International Conference on Cyber Security and Resilience, IEEE, 26-28 July, 2021. DOI: 10.1109/CSR51186.2021.9527915 OPEN ACCESS
  28. C. Iliou, T. Kostoulas, T. Tsikrika, V. Katos, S. Vrochidis, I. Kompatsiaris, "Detection of advanced web bots by combining web logs with mouse behavioural biometrics.", Digital Threats: Research and Practice (DTRAP), vol. 2, no. 3, pp. 1 - 26, 2021. DOI:10.1145/3447815 OPEN ACCESS
  29. K. Gkountakos, K. Ioannidis, T. Tsikrika, S. Vrochidis, I. Kompatsiaris, "Visual Recognition of Abnormal Activities in Video Streams.", in Technology Development for Security Practitioners, Cham: Springer International Publishing, pp. 151-165. OPEN ACCESS
  30. K. Gkountakos, K. Ioannidis, T. Tsikrika, S. Vrochidis, I. Kompatsiaris, "Crowd Violence Detection from Video Footage.", in Proceedings of the 2021 International Conference on Content-Based Multimedia Indexing (CBMI), IEEE, June 2021. OPEN ACCESS
  31. B. Akhgar, M. Gercke, S. Vrochidis, H. Gibson (2021). Dark Web investigation. 288 Pages, Springer.
  32. K. Gkountakos, D. Galanopoulos, M. Mpakratsas, D. Touska, A. Moumtzidou, K. Ioannidis, I. Gialampoukidis, S. Vrochidis, V. Mezaris, I. Kompatsiaris, "ITI-CERTH participation in TRECVID 2020.", in Proceedings of the TRECVID 2020 Workshop, Gaithersburg, MD, USA, December 2020. OPEN ACCESS
  33. G. Orfanidis, K. Ioannidis, A. Tefas, S. Vrochidis, I. Kompatsiaris, "A modified Single-Shot multibox Detector for beyond Real-Time Object Detection.", in Proceedings of the 25th International Conference on Pattern Recognition, (ICPR 2020), Milan, Italy, 10 & 15 January 2021.
  34. D. Chatzakou, J. Soler-Company, T. Tsikrika, L. Wanner, S. Vrochidis, I. Kompatsiaris, "User Identity Linkage in Social Media Using Linguistic and Social Interaction Features.",in Proceedings of the 2020 ACM on Web Science Conference, July 6-10, 2020. OPEN ACCESS
  35. K. Gkountakos, K. Ioannidis, T. Tsikrika, S. Vrochidis, I. Kompatsiaris, "A Crowd Analysis Framework for Detecting Violence Scenes.", in Proceedings of the 2020 International Conference on Multimedia Retrieval (ICMR ‘20), Dublin, Ireland, June 8–11, 2020, pp. 276 - 280. OPEN ACCESS
  36. A. Koufakis, D. Chatzakou, G. Meditskos, T. Tsikrika, S. Vrochidis, I. Kompatsiaris, "Semantic Web Technologies in Fighting Crime and Terrorism: The CONNEXIONs Approach.", in Proceedings of the 1st International Workshop on IoT infrastructures for safety in pervasive environments (IoT4SAFE), Invited talk, 2 June, 2020. OPEN ACCESS
  37. K. Gkountakos, K. Ioannidis, S. Vrochidis, I. Kompatsiaris, "ITI-CERTH participation in TRECVID 2019.", in Proceedings of the TRECVID 2019 Workshop, Gaithersburg, MD, USA, November 2019. OPEN ACCESS
  38. A. Katmada, G. Kalpakis, T. Tsikrika, S. Vrochidis, I. Kompatsiaris, "An extensible framework for interactive real-time visualizations of large-scale heterogeneous multimedia information from online sources.", in Proceedings of the International Conference on Multimedia Modeling (MMM2020), Special Session on “Multimedia Analytics: Perspectives, Tools and Applications”, Daejeon, Korea, 5-8 January 2020.
  39. S. Andreadis, A. Moumtzidou, K. Apostolidis, K. Gkountakos, D. Galanopoulos, E. Michail, I. Gialampoukidis, S. Vrochidis, V. Mezaris, I. Kompatsiaris, "VERGE IN VBS 2020.", in Proceedings of the 26th Int. Conf. on Multimedia Modeling (MMM2020), Daejeon Convention Center (DCC), Korea, 5-8 January 2020. OPEN ACCESS
  40. N. Bastas, G. Kalpakis, T. Tsikrika, S. Vrochidis & Y. Kompatsiaris, "A comparative study of clustering methods using word embeddings", in Proceedings of the 2019 European Intelligence and Security Informatics Conference (EISIC 2019), Oulu, Finland, 24-26 November 2019. https://ieeexplore.ieee.org/document/9108898
  41. P. Panagiotou, G. Kalpakis, T. Tsikrika, S. Vrochidis, I. Kompatsiaris. "Query reformulation based on word embeddings: A comparative study". Technology Advances and Support for Security Practitioners of the Security Informatics and Law Enforcement book series. OPEN ACCESS
  42. P. Mitzias, E. Kontopoulos, J. Staite, T. Day, G. Kalpakis, T. Tsikrika, H. Gibson, S. Vrochidis, B. Akhgar, & Υ. Kompatsiaris, "Deploying Semantic Web Technologies for Information Fusion of Terrorism related Content and Threat Detection on the Web", Proceedings of the Security Analytics and Cyber Threat Intelligence on the Web (SACTI 2019) workshop, in conjunction with the IEEE/WIC/ACM International Conference on Web Intelligence (WI 2019), Thessaloniki, Greece, 14-17 October 2019. OPEN ACCESS
  43. C. Iliou, T. Kostoulas, T. Tsikrika, V. Katos, S. Vrochidis, and Y. Kompatsiaris, "Towards a framework for detecting advanced Web bots", Iin Proceedings of the 14th International Conference on Availability, Reliability and Security, p. 18. ACM, 2019. OPEN ACCESS
  44. I. Gialampoukidis, S. Vrochidis, I. Kompatsiaris, and I. Antoniou. “Probabilistic density-based estimation of the number of clusters using the DBSCAN-martingale process”. Pattern Recognition Letters, Vol. 123, pp 23-30, 4 March 2019. OPEN ACCESS
  45. G. Kalpakis, T. Tsikrika, S. Vrochidis, I. Kompatsiaris, "Identifying terrorism-related key actors in multidimensional social networks", in Proc. 25th Int. Conf. on Multimedia Modeling (MMM2019), Thessaloniki, Greece, Jan. 2019. OPEN ACCESS
  46. C. Iliou, T. Tsikrika, G. Kalpakis, S. Vrochidis, I. Kompatsiaris, "Adaptive focused crawling using online learning: A study on content related to Islamic extremism", in 5th International conference ‘Internet Science’ (INSCI’2018), 24-26 October 2018, St. Petersburg, Russia. OPEN ACCESS
  47. G. Kalpakis, T. Tsikrika, I. Gialampoukidis, S. Papadopoulos, S. Vrochidis, I., Kompatsiaris, "Analysis of Suspended Terrorism-Related Content on Social Media", Community-Oriented Policing and Technological Innovations, 107-118. OPEN ACCESS
  48. G. Kalpakis, T. Tsikrika, I. Gialampoukidis, S. Papadopoulos, S. Vrochidis, I. Kompatsiaris. "Analysis of Suspended Terrorism-Related Content on Social Media". In Community-Oriented Policing and Technological Innovations, Springer Briefs in Policing, Springer, 27 April 2018. OPEN ACCESS
  49. C. Iliou, G. Kalpakis, T. Tsikrika, S. Vrochidis, I. Kompatsiaris. "Hybrid Focused Crawling on the Surface and the Dark Web". EURASIP Journal on Information Security, vol. 2017, no. 11, 4 July 2017. OPEN ACCESS
  50. M. Zampoglou, S. Vrochidis, A. Rocha, V. Katos (Eds.). (2017). MFSec '17: Proceedings of the 2nd International Workshop on Multimedia Forensics and Security. Bucharest, Romania, 2017. Association for Computing Machinery, 30 June 2017. OPEN ACCESS
  51. B. Akhgar, P. Bertrand, C. Chalanouli, T. Day, I. Fragkiadakis, H. Gibson, D. Kavallieros, E. Kermitsis, I. Kompatsiaris, E. Kyriakou, G. Leventakis, E. Lissaris, S. Mille, D. Myttas, T. Tsikrika, S. Vrochidis, U. Williamson. "TENSOR: Retrieval and Analysis of Heterogeneous Online Content for Terrorist Activity Recognition". Proceedings of the Estonian Academy of Se-curity Sciences: Secure Societies, 15 June 2017. OPEN ACCESS
  52. I. Gialampoukidis, G. Kalpakis, T. Tsikrika, S. Papadopoulos, S. Vrochidis, I. Kompatsiaris, "Detection of Terrorism-related Twitter Communities using Centrality Scores", in Proceedings of International Workshop on Multimedia Forensics and Security (MFSec 2017), Bucharest, Romania, June 06, 2017. OPEN ACCESS
  53. T. Tsikrika, B. Akhgar, V. Katos, S. Vrochidis, P. Burnap, M. L. Williams, "1st International Workshop on Search and Mining Terrorist Online Content & Advances in Data Science for Cyber Security and Risk on the Web". In Proceedings of the Tenth ACM International Conference on Web Search and Data Mining (WSDM 2017), pp. 823-824, Cambridge, UK, February 2017. OPEN ACCESS
  54. G. Kalpakis, T. Tsikrika, N. Cunningham, C. Iliou, S. Vrochidis, J. Middleton, I. Kompatsiaris. "OSINT and the Dark Web". In Open Source Intelligence Investigation - From Strategy to Implementation, B. Akhgar, P. S. Bayerl, F. Sampson (Eds.), Springer, 3 January 2017. OPEN ACCESS
  55. I. Gialampoukidis, T. Tsikrika, S. Vrochidis, I. Kompatsiaris,"Community Detection in Complex Networks Based on DBSCAN* and a Martingale Process", in 11th International Workshop on Semantic and Social Media Adaptation and Personalization (SMAP), 2016, pp. 1-6. IEEE.
  56. C. Iliou, G. Kalpakis, T. Tsikrika, S. Vrochidis, I. Kompatsiaris,"Hybrid Focused Crawling for Homemade Ex-plosives Discovery on Surface and Dark Web", 11th International Conference on Availability, Reliability and Security (ARES 2016), Salzburg, Austria, Aug 2016. DOI: 10.1109/ARES.2016.66
  57. I. Gialampoukidis, G. Kalpakis, T. Tsikrika, S. Vrochidis, I. Kompatsiaris,"Key player identification in terrorism-related social media networks using centrality measures", in Intelligence and Security Informatics Conference (EISIC), 2016 European, pp. 112-115. IEEE, 2016. DOI: 10.1109/EISIC.2016.029
  58. G. Kalpakis, T. Tsikrika, C. Iliou, T. Mironidis, S. Vrochidis, J. Middleton, U. Williamson, I. Kompatsiaris,"In-teractive Discovery and Retrieval of Web Resources Containing Home Made Explosive Recipes", in 4th International Conference on Human Aspects of Information Security, Privacy and Trust, Toronto, Canada, 17 - 22 July 2016.
  59. T. Tsikrika, G. Kalpakis, S. Vrochidis, I. Kompatsiaris, I. Paraskakis, I. Kavasidis, J. Middleton, and U. Williamson, "A Framework for the Discovery, Analysis, and Retrieval of Multimedia Homemade Explosives Information on the Web", in Proceedings of the International Workshop on Multimedia Forensics and Security (MFSec 2015), held in conjunction with the 10th International Conference on Availability, Reliability and Security, Toulouse, France, 2015. https://doi.org/10.1109/ARES.2015.86
  60. G. Kalpakis, T. Tsikrika, F. Markatopoulou, N. Pittaras, S. Vrochidis, V. Mezaris, I. Patras, and I. Kompatsiaris, "Concept Detection on Multimedia Web Resources about Home Made Explosives", in Proceedings of the International Workshop on Multimedia Forensics and Security (MFSec 2015), held in conjunction with the 10th International Conference on Availability, Reliability and Security, Toulouse, France, 2015. DOI: 10.1109/ARES.2015.85