The attempt by law enforcement authorities in Boston to use crowdsourced video images and still photos to identify those responsible for the fatal bombings in the city earlier this week could prove challenging, but it's not unprecedented.
In 2011, the city of Vancouver, British Columbia, resorted to a similar tactic to identify the main participants in a riot in the city following a loss by the Vancouver Canucks to the Boston Bruins in Game 7 of the Stanley Cup finals. The riot resulted in more than 100 injuries and $4.5 million in damages to vehicles and businesses.
To identify the ringleaders, the Vancouver Police Department's riot investigation team gathered more than 1,600 hours of video images and nearly 1 million digital images in dozens of different formats from the public, the media and closed-circuit TV cameras in the city.
A team of 50 forensic analysts from the Law Enforcement and Emergency Services Video Association (LEVA) in Indianapolis, helped the Vancouver police analyze the images. Working out of a multimedia evidence-processing lab at the University of Indianapolis, the team of analysts first converted the video images into a standard format and loaded them into centralized video servers from where the images could be accessed by several people.
Working around the clock over a two-week period, the analysts reviewed the footage and added metadata and unique identification markers to describe individuals and specific events, such as the time or location where an incident might have occurred or the direction in which an individual might have been heading. More than 15,000 events were tagged as criminal acts using this process.
The infused metadata allowed investigators to search through the images and to track individual behavior and events between video footage from multiple sources, said Grant Fredericks, an instructor at LEVA and technical manager of the forensics effort. The analysis resulted in criminal charges brought against more than 200 individuals involved in the rioting.
The city's effort remains one of the largest video forensics efforts involving crowdsourced video and images.
The same approach can also be used in the Boston investigations, but the sheer volume of data will make the task harder, said Fredericks, who is also a video analysis instructor at the FBI National Academy in Quantico, Va., and the founder of Forensic Video Solutions.
"When you have an incident like Monday in Boston where you have 150,000 to 200,000 people -- a significant percentage of those people have cell phones and they are taking pictures and video," Fredericks said, "Every single one of them was potentially collecting evidence for this investigation," Fredericks said. "There are probably hundreds of people with footage showing the person or persons who left the bomb," without their knowing it, he said.
Law enforcement authorities investigating the Boston Marathon bombings on Tuesday called on citizens to turn in any video footage or digital images they might have taken at the event. According to Boston Police Commissioner Ed Davis, investigators intend to go through "every frame of every video" in their possession to track down the perpetrators of the attacks that killed three people and injured more than 170 others.
The immediate task for Boston investigators will be to ensure that they have a good process in place for gathering video and digital images turned in by the public, Fredericks said. In Vancouver, many of those who sent in video of the riots edited the footage or changed file formats while submitting their videos and compromised the integrity of the footage in the process, he said.