After the FBI circulated photos of two suspects in the Boston Marathon bombings on Thursday afternoon, a thread on the social media site Reddit suggested that one of the wanted men could be a missing student from Brown University in Rhode Island.

Online speculation that followed sent Sunil Tripathi's name trending worldwide on Twitter. News crews descended on his family home in surburban Philadelphia. Hours later, however, NBC News was reporting that "Tripathi was not involved with the bombings at all."

In fact, the two suspects in the FBI photos are believed to be brothers originally from a Russian region near Chechnya. One was arrested Friday night after a massive police manhunt, while the other was killed earlier after gunfire was exchanged with police.

But the brothers didn't seem to figure prominently in any of the widespread amateur sleuthing online that emerged after the bombings. Suspects whose images were front and centre in the public's online speculation ranged from a suspicious man in a blue robe seen in the area around the time of the bombings, to another person who ran away from the scene very quickly after the first explosion on Monday.

The haste with which such images and speculation flooded social media sites such as Reddit and 4chan after the bombings is hardly surprising. In the face of such deadly horror at such an iconic public event, everyone wanted a perpetrator behind bars instantly.

Plus, maybe one of those photos would be the crucial clue that could crack the case wide open.

But the online sleuthing fuelled by the ubiquity of cellphones and their ability to capture every face and activity in their vicinity also highlights a question about the role such activities can play in solving crime. In short, do they do more harm than good?

"There are vigilante-type concerns here, obviously," says Peter Rosenthal, a lawyer and adjunct professor of law at the University of Toronto.

"It's one thing if people gather photographs or videos and turn them in to the proper authorities for analysis. That's obviously a positive thing to do, it seems to me.

"But on the other hand, to be all over the internet identifying people as suspects could be very dangerous for those persons who get identified."

Rosenthal recognizes the trickiness of the situation, with everyone wanting an arrest in the Boston bombings. But he also sees a significant need for caution in such instances.

"That's the kind of situation that leads to wrongful convictions even in court," not to mention a wrongful identification that "can end up with somebody getting beaten or killed. It could be dangerous."

Leave it to the professionals

Rosenthal suggests leaving any examination of potential evidence to the professionals. But that is by no means the only view on this contentious subject.

Sidneyeve Matrix, a media professor at Queen's University in Kingston, Ont., recognizes the inherent danger in the possible identification of people who aren't suspects. But she argues that the kind of crowdsourced investigative work occurring around the Boston bombings, does "great good."

Massive online participation can solve problems quickly, she says.

"Having a thousand sets of eyeballs or a million sets of eyeballs … is handy because the wisdom of the masses can come together to solve problems a lot quicker sometimes. It's a speed issue, really."

Misinformation and false leads are risks in every avenue of investigation, she says.

"I think we can probably identify misinformation and then take it off the table a lot quicker when we have lot more people involved, including professionals and amateurs, working together."

A middle ground

In this case, the actions of Reddit and other online sites have drawn considerable media discussion and criticism.

"Our crowd-mobbed vigilante future," was the headline on a piece in Salon. The Atlantic waded in with "Hey Reddit, Enough Boston Bombing Vigilantism."

For its part, Reddit has added some words of explanation to its FindBostonBombers thread, saying that it does not condone vigilante justice.

"FindBostonBombers seeks a middle ground," Reddit editors say in notes down the side of a web page displaying a discussion. "A middle ground populated with debate tempered with cautious restraint. We ask that all viewers and subscribers pursue our goal dispassionately and impartially as possible.

"We do not support any form of vigilante justice. We are not law enforcement. If you have major information about the identities of any of the bombers, please send a tip to the FBI or [Boston Police Department]."

The RCMP declined to be interviewed about this topic, but said in an email that "for reasons such as the safety of the victims, interest in public safety and protecting the integrity of police investigations, the RCMP does not advocate vigilantism." 

In Tripathi's case, his mis-identification by members of the public as a possible suspect led to news vans descending on his family's home in suburban Philidelphia, according to a report on philly.com.

No one answered the door, the report said, but "a statement posted on a 'Help Us Find Sunil Tripathi Facebook,' which at one point was taken down and then posted again, said: 'A tremendous and painful amount of attention has been cast on our beloved Sunil Tripathi in the past twelve hours.'

"We have known unequivocally all along that neither individual suspected as responsible for the Boston Marathon bombings was Sunil."

Don't blame social media

Of course, any vigilante action would ultimately depend on someone deciding to take that step, but University of British Columbia journalism professor Alfred Hermida suggests that social media shouldn't take the blame for vigilantism.

"The truth isn't in the individual fragment. It's in the overall discussion of all these conversations."

Hermida says that too often it's the mainstream media that takes online comments and amplifies them, distorting their importance. What appears online is simply raw, unfiltered information.

"This is the process of journalism, the process of investigation, happening before our eyes."

And that process has been evolving as technology — and social media — have been changing.

Toronto Police spokesman Mark Pugash says that, over the years, technology has opened a number of investigative avenues.

"One is the ability to send information to more people more quickly than ever before, but it's also the ability to view what's in open-source locations. Developments with [closed-circuit] CCTV cameras have made a fundamental difference to police investigations."

Challenges with any evidence

Pugash says the difficulty that can arise around online information turning out to be incorrect is the same as could develop in any investigation.

"You have to determine whether what you're seeing is accurate or not, if it represents what it claims to represent or not, if it's been altered or if it hasn't. But those are challenges you have with any evidence."

Still, someone has to sort through all the evidence if any investigation is to progress.

"The important factor here is that it's going to take old-fashioned police work, it’s going to take humans, it's going to take human journalists that can go through all of this information that’s being created," says Matrix.

She considers what has evolved online around the Boston bombings to be "a perfect example of using social media for social good."

"It's a textbook of how we're getting better at this. We're pulling together and we're responding more quickly, more professionally. We have more responders."

She also thinks that we've only seen the beginning of the role social media will play in police investigations. "It's early days, and it's not going anywhere."

With files from the CBC's Chris Brown