As investigators try to figure out what happened today during the bombings at the Boston Marathon, they'll turn to video taken at the scene of the explosions.
In addition to any closed-circuit television cameras lining Boylston Street and its surroundings, The Bureau Chief of Public Information, Cheryl Fiandaca, called for members of the public to send in video from near the finish line.
Once the police have the prospective evidence in hand, they'll need to run forensic analysis on it. What we know from recent years is that the amount of evidence can be staggering large. For example, the Vancouver riot in early 2011 brought 1,600 hours of video streaming into that city's police department. Just to watch all that video through one time is a substantial task, let alone examining it closely or trying to find events or people of interest.
Right now, there is no video software that can do this type of analysis, not even in a first-pass way. IARPA (DARPA for the intelligence services) put out a call for proposals in 2010 for this kind of "Automated Low-level Analysis and Description of Diverse Intelligence Video." It described, in brief, the problem that investigators (or intelligence analysts) face:
Massive numbers of video clips are generated daily on many types of consumer electronics and uploaded to the internet. In contrast to videos that are produced for broadcast or from planned surveillance, the "unconstrained" video clips produced by anyone who has a digital camera present a significant challenge for manual as well as automated analysis.
So, at the moment, human investigators must watch and code each and every second of the video that they collect. While the Boston police may have the resources they need, chances are that they're going to be swamped with video from the scene, given the number of spectators and the prevalence of cameras. This is the future we live in: Major events are photographed and recorded by hundreds of people.
Until we know more about the bombings, we don't know under whose jurisdiction the investigation will come. The Federal Bureau of Investigation analyzes video within its Operatonal Technology Divison, inside the Digital Evidence Laboratory by the Forensic Audio, Video, and Image Analysis Unit (FAVIAU). In 2010, that unit had just 26 agents.
If Federal or local police do need help, they could reach out to Digital Media Evidence Processing Lab at the University of Indianapolis, which is run by the Law Enforcement and Emergency Services Video Association.
The lab has 20 video workstations running Ocean Systems dTective forensic video software. It's set up for training police in video forensics, but has been envisioned as a place that could serve as a headquarters for emergencies like the one in Boston.
After the Vancouver riots, police in that city brought the video they received from citizens to the lab. "Working around-the-clock shifts, analysts and technicians examined more than 5,000 hours of video while tagging more than 15,000 criminal events and individuals," trade journal Evidence Magazine wrote in 2012. "The approach proved quite powerful. Whereas investigators required four months to process just 100 hours of video after the riots in 1994, the thousands of hours of video recorded in 2011 were processed and initially tagged in just two weeks."
This will become the sad new ritual of mourning a tragedy: sending and processing the horrific memories of an event in hopes of finding evidence to bring criminals to justice.