Evan Schuman's StorefrontBacktalk

Loss Prevention security footage from a Boston Lord & Taylor located across the street from where two bombs had detonated near the Boston Marathon finish line on Monday (April 17) captured footage of someone leaving the bag with the bomb in position. This is far from the first time retail security video has been used to help solve a crime that does not directly involve that retailer, but it might go down as one of the most historic.

The bombing, which killed three people and injured 176 others, was one of the more devastating terrorist attacks in the U.S.. The footage from a surveillance camera at Lord & Taylor “has provided clear video of the area” but law enforcement officials were initially vague about what was captured, according to The Boston Globe. “The camera from Lord & Taylor is the best source of video so far,” said Dot Joyce, a spokeswoman for Boston Mayor Thomas M. Menino. The Lord & Taylor video showed the suspect looking up and it was was able to capture a clear image of the suspect’s face.

Although some countries (notably England) have saturated urban areas with government surveillance cameras, in the U.S., most non-private cameras are devoted to either traffic or transit safety, which makes them much less useful for anything that doesn’t actually happen in the street or a mass-transit station.

That makes external retailer LP cameras—which are typically focused on sidewalks, doorways and other areas where people are standing or walking near the store—a major source of evidence for crimes that happen nearby. Merchants have an incentive for going with the best cameras they can afford rather than with the lowest bidder: The sharper the image, the better the chance to catch a thief—or a killer.

The retail video was just one of many videos law enforcement was reviewing and some of the videos “also showed at least a handful of others whom the authorities want to question, either because of what they appear to be doing in the video or their proximity to the blasts, a senior law enforcement official said,” according to a report in The New York Times.

The official said the authorities were trying to boil down the number of people of interest in the videos and would then decide whether to ask the public’s help in locating them.

“It’s a crowd, there are a lot of different angles. It is not like some television-produced video — there’s a lot that isn’t clear,” said the official. “But most interpretations support the notion that one man is seen dropping a bag.” The official added: “There are several videos with people in them, and we’re looking to talk to more than one guy. It’s still very squishy but there are a lot of interesting people” the authorities want to talk to.

The Times story also confirmed that authorities are not certain the name of the person seen in the Lord & Taylor video, apparently placing the bomb. The F.B.I. is still “looking for a name to put with a face in a video,” one law enforcement official said, speaking on the condition of anonymity, The Times said.