Was it the man in the blue robe? The blue-jacket “Backpack Bros”? The black-jacket “Backpack Bros”? “Mr. Cardigan?” “Bending Over Guy + Buddy?”

These are among the flurry of questions now under consideration at the social networking sites Reddit and 4Chan, which are hosting a fascinating and slightly dangerous crowdsourcing investigation of Monday’s Boston bombings. The sub-Reddit “Findbostonbombers” is awash in debate, speculation, clues, circled pictures, arrows pointing from one guy to the next, and the repeated identification of people who may wind up being innocent, albeit even if none of the photographs are labeled with real names.

One of the more popular threads discusses “Blue Robe Guy,” comparing images of a man with a beard “clenching” a black backpack with white (or silver) stripes on the shoulder straps. He has the straps draped over one arm, as opposed to wearing it on his shoulders, which is making Reddit users suspicious.

“Who holds a backpack that way, and closely resembles him trying to protect something possibly,” wrote user Toke_Blue. “The fact that the same back pack is exploded o [sic] the ground kind of strikes a match in my book.” Adds RobotDeathSquad: “Also note that in the very far right pic, he is clutching his hand with a very tight grip as if the backpack is really heavy.”

It goes on like that for hundreds of comments, and just about this one guy. Would he really hold it like that if the bag was heavy? Wouldn’t that tire out his arms? Do the straps seem like they’re pulling on his arm, indicating substantial weight? Is he holding it where he is so he can quickly dump it?

And that’s just one “suspect.” This page collects a series of images compiled by users who have scanned through thousands of them for clues: black backpacks, people seemingly uninterested in the marathon, and—sadly—“ethnic” people. The amateur sleuths have compiled a spreadsheet, even complete with a “suspect summary” that describes three of the five as “ethnic” and four of the five as “unlikely,” because of reasons described in a different column.

Is the Internet moving faster than the FBI? It’s impossible to know, of course. The authorities aren’t crowdsourcing their clues. They could already have all of these pictures, a list of suspects 10 times longer, as well as tips from people who were really at the marathon and really saw things.

Is Reddit about to create the next Richard Jewell? Its users are hyperaware of that possibility, as they’ve demonstrated by the most popular post in the Boston Bombing thread: “Does Anyone Remember Richard Jewell?”

“This sub is dedicated to pointing to random people in a crowd photograph and declaring your suspicions. You're starting the trial by public aspect,” the poster wrote. “Who knows? You may get lucky and your pet suspect turns out to be the bomber. But I've seen at least 10 people singled out, and not all of you are correct. You should be very very careful about picking and choosing who you think might have killed three people and wounded many more, based on where they were standing and if they were carrying a backpack or not.”

That kicked off a whole new round of discussion, wherein most agreed that the thing to do with this information is report it to the authorities and not actually try to put names to faces or hunt people down and interrogate them. One user noted that the perpetrator could actually be on Reddit himself, trying to throw people off his own scent. After some back and forth, the Boston Bombing thread’s moderator put up this list of seven things to remember — among them, that the aim is “simply to provide tips for the FBI” and “DO NOT POST ANY PERSONAL INFORMATION.”

With bated breath, the world is waiting for some news about who committed Monday’s atrocity, in part because people are, with good reason, afraid that the string of attacks has yet to end. If nothing else, The “Findbostonbombers” Reddit thread gives its participants an outlet for anxiety. Or, as one user put it: “I think people are here because it gives them some semblance of control over a tragedy that they otherwise have no influence over.”