Crowd sourcing is only good at some very important tasks, but was truly terrible and libelous in an information vacuum. Reddit deserves some credit for Thursday night successes of the forum, but ultimately old fashioned police work was key in this specific case.
The "witch hunt" summary is accurate for the Monday to Thursday 5PM time, when so much was said that was unprovable, and much more difficult to disprove, like the NY Post photos of innocent people accused of being the terrorists, taking too many days to be seen as extremely wrong.
FBI OFFICIAL PHOTOS
After the FBI released Official Suspect photos at about 5PM Thursday, April 18, 2013, Reddit (or rather Subreddit "findbostonbombers") had some commenters who were actually very useful, and had contributions which were well substantial and well ahead of the media.
DAVID GREEN PHOTO
The David Green photo from the corner of Fairfield Street and Boylston Street just after the bombing was there, less than 2 hours after the FBI official suspect photo release, and more than 3 hours before it was on NY Times 11:14 PM published website article, and apparently also the CNN Piers Morgan interview of David Green the same late night. The Monday photo showed Suspect #2, with the white hat, with the smoke from both bombs visible, walking around the corner of Fairfield Street directly toward MIT campus, foreshadowing events late Thursday night, including the murder of the MIT police officer.
http://thelede.blogs.nytimes.com/2013/04/18/new-higher-resolution-image-of-boston-marathon-suspect-emerges/
SUSPECT HAT IDENTIFICATION
The crowd sourcing found the official web catalog photos of both hats make/model/catalog-photos used by the terrorists. This is a quickly verifiable task, that the subreddit did very well. I suspect that all such commodity product identifications can be done fastest with most accuracy, by a large crowd that cares, such as was the case on Reddit that night. Reddit found links to the official web catalog photos of these hats, under ideal circumstances.
This is not the first time either, a prior case was solved by a sharped eyed reddit user identified a Cadillac 1990 head light from a crime scene photo, helping resolve that case.
The hat ID was potentially extremely useful for several reasons; More witnesses could be asked about the clear photos of the hats, helping the FBI. Also, somewhat technical, but the FBI could use computational clarifying techniques, using these identified and purchasable hats, to calculate a clearer image from fuzzy source photos of the faces of the Subjects in the photos. Admittedly these computer image refinement techniques are more familiar to astronomers than crime fighting, more like the CSI type TV shows than real life law enforcement, but it would be possible.
OTHER PHOTOS ON REDDIT AFTER 5PM THURSDAY
At least two other photos of the official FBI Suspects, not then available, were found and shared on Reddit. I have not seen either of these photos in the press.
Photo link: before the bombing possibly Suspect #1 black hat from behind, headed east on Boylston from about the Starbucks, (next to her ring). Less likely but possibly Suspect #2 far left (under her elbow).
http://imgur.com/a/34wtj
Photos link: Potentially a very damning photo, possibly Suspect #2, with the backwards white cap on, a back pack on ground, and possible 8 year old victim still alive. (the younger Tsarnaev brother is accused of being Suspect #2), a back pack on the ground, behind possibly the 8 year old bombing victim who was killed by a bomb blast.
http://imgur.com/a/fEZhX
DETAIL FROM IMAGES
Although guessing who the terrorists were was something that Reddit utterly failed at, libeling many people Monday to Thursday 5PM, once the FBI released official Suspect photos, a sharp eyed commenter spotted countless details such as the woman in the far right of the David Green photo of Fairfield, in a Tufts Lacrosse sweat shirt, appears to the be the same woman standing next to (possibly) the 8 year old victim in the unexploded backpack on the ground photo I just mentioned. Possibly the same woman in both photos. The millions of eyeballs looking at these photos found that visual connection very rapidly, something that even an art major (for while) with perfect eyesight like me would have easily missed. Although she might not have seen anything recorded better in either picture, she would be one of the best uninjured witnesses law enforcement could find.
A sharped eyed Reddit reader noticed the Starbucks photo also has a backwards white capped person on the far left of the image, under her elbow, suggested to be Suspect #2/white cap/younger Tsarnaev, but I find very hard to determine if it is him, because it requires much better tools and knowledge than I have, to confirm that theory.
LEAKED PHOTOS
Reddit commenter posted links to a very graphic (probably inflammatory) photo described as the dead older Tsarnaev brother in hospital or morgue. Reddit suggested that a Boston PD member twitter leaked it, and then shut down the account. Weather that link should be there is profoundly complex free speech question. I think it should be there, but could create serious blow back for someone.
LESSON LEARNED?
Reddit is crowd sourcing website. Any crowd sourcing website needs more moderators to remove libelous non-sense, because angry mobs spew too much fear and jump to too many false conclusions. Crowd sourcing moderators must play to its crowds strengths, such as collecting photos and videos, and links to same, from many people to collect as many different photos as possible. Crowd sourcing websites that have real information, such as law enforcement official photos of commodity items without detail id (make/model), belonging to criminals/terrorists, such as the baseball caps, need to quickly identify what these commodity items are, because someone in the crowd will know the actual make/model/weblink/officialwebcatalogphoto of these items. Crowd sourcing is going to be much faster and more accurate than asking too few media or law enforcement to do the same. Once identified, such as backpacks and hats, law enforcement can find production and sales information much more quickly, but only if they have id of the gear.
HOW WAS THIS CASE REALLY SOLVED? (ACCORDING TO ONLY INITIAL PARTIAL REPORTS)
Jeff Bauman who lost both legs, woke up from double amputation, and wrote down who he saw, communicating to the FBI who the bomber was. FBI did the hunt for basic video and photos, using security tapes from fixed cameras nearby, and released the photos. FBI crowd sourcing the entire news watching world worked. Some people who knew the brothers answered the FBI request and told the FBI the brothers names as the possible terrorists, along with thousands of people sending in thousands of other names. The publication of the photos triggered strong reaction or panic in the accused terrorist. They went shopping, paying for their food, at the Kendall Square 7-11, and were spotted, and someone contacted the police. Police responded, and the press was told the police were responding to a robbery. Then all hell broke loose. The brothers killed an MIT police officer. They may have attempted to steal a police car to escape Boston more easily, or perhaps even been stopped by the cop, I have not heard which theory is preferred by law enforcement, perhaps neither theory.
None of these events involved open web crowd sourcing. Perhaps next time, if the terrorists were more organized, requiring a longer man hunt, would the crowd sourcing been more helpful.
CONCLUSION
Hopefully sites like Reddit will play to their strengths from now on.