The video Philadelphia police posted online represented a major break in a horrific case - capturing images of a group suspected in a vicious Center City attack on a gay couple.
The suspects in the video - a group of young men and women laughing, smiling, and dressed for a night out - had allegedly mocked two men walking near Rittenhouse Square before beating them badly, sending both to the hospital. One of the men was also robbed, police said.
Word spread, and within hours, people took to Twitter and the Internet, trawling through social media in an attempt to identify the men and women in the video and forwarding their findings to police.
As detectives in the case zeroed in on the suspects and fielded tips, the online effort to identify them became something of a crowdsourced investigation.
"This is the largest public display that I've seen of crowdsourcing to get info for crime victims," said Sgt. Eric Gripp of the Police Department's Public Affairs unit. "We receive a lot of info daily about the videos we post. We don't seem to see it to the scale that this was."
No arrests have been made, and the investigation is ongoing.
But by Wednesday, lawyers for several members of the group who allegedly attacked the couple had told police that their clients would be "coming in to give their sides of the story," Gripp said, and the Twitter campaign had made national news.
Investigators had spoken to several persons of interest as of Wednesday night, with more interviews possible, a police source said.
Capt. Frank Banford of Central Detectives, which is handling the case, said his investigators had many tips and many interviews to do.
"This will go methodically and thoroughly," he said.
For a week since the attack on Sept. 11, police had worked to find surveillance video, and the footage they eventually found was unusually clear.
A Twitter user who goes by the handle @FanSince09 - and who ordinarily tweets about Philadelphia sports - was "horrified" by reports of the attack and then was struck by the clarity of the footage.
"These people are captured clear as day. You can see the faces, you can see what they're wearing," he said in a telephone interview. The man, who asked not to be identified so as to maintain his anonymity on Twitter, said he decided to take action. He began writing a series of tweets encouraging his followers to try to identify the people in the video.
Then, a reality-TV star from New Jersey posted a photo taken at an upscale restaurant purporting to show the subjects in the video.
That's when @FanSince09 and about a dozen friends on the site used Twitter and Facebook to try to identify where the photo had been taken and who was in it. They forwarded their findings to Detective Joe Murray, who runs a popular Twitter account, and he, in turn, passed the information to the detectives working the case.
"If this is one example of something happening, imagine the future of what else you can do with social media," Murray said. "With Twitter, I have tens of thousands of eyes that can look and help."
Kenneth A. Gavin, a spokesman for the Archdiocese of Philadelphia, released a statement Wednesday in response to reports that former students at Archbishop Wood High School may have been involved in the attack.
"This afternoon, administrators communicated with the entire Archbishop Wood school community to make it emphatically clear that the school does not, under any circumstances, tolerate or condone the violent and hateful behavior displayed by those who took part in this senseless attack," Gavin said. "The actions of those who took part in the attack are reprehensible and entirely unacceptable. They are not an accurate reflection of our Catholic values or of Archbishop Wood High School."
Gavin said that one person reportedly involved in the attack was an assistant basketball coach at Wood and that he had been fired Wednesday night. He said the man was not a teacher but worked under a contract.
Gripp said that the department was grateful for help from @FanSince09 and others and that it encouraged officers to engage with the public on Twitter.
"We want people to get to know the officer themselves as a human being. When that happens, people feel comfortable reporting information," he said. "As the Internet has shown us, people are not shy about voicing their complaints online - there are people that would never call 911, never go to a police station, but they're comfortable on Twitter."
Still, referring to some erroneous reports that "the crime had been solved," he stressed that the investigation was ongoing and that online sleuths should remain cautious about publicly implicating potential suspects, lest they get it wrong.
@FanSince09 said he and other Twitter users "worked with police and not as police," turning over tips instead of publicly naming potential suspects.
"I'm glad this was done quietly and professionally," he said.
Gripp said that the department had been encouraged by Tuesday's social-media outpouring - and that he hoped would-be tipsters would show "the same fervor and support" in other cases.
"We need the help of the public."
Inquirer staff writer Robert Moran contributed to this article.