One week ago, Tamerlan and Dzhokhar Tsarnaev walked through a crowd at the Boston Marathon and dropped homemade bombs near the finish line, killing three people and injuring more than 180 others. While investigators wait to question Dzhokhar, who is being held at the Beth Israel Deaconess Medical Center in Boston, homeland and national security experts are looking to U.S. processes and policies for identifying violent extremists and implementing stronger security measures at public events.

National security expert and principal at Catalyst Partners Dave McWhorter spoke to Canada news broadcast CTV about the hunt for the Boston bombers, foreseeing that the best evidence would be found in the myriad videos and pictures from the attack. Check out McWhorter’s insight into the ongoing investigation and how the incident will impact security at sporting events and other public gatherings in the future.