According to police spokesman Donny Moses, he is 31 years old and from Arlington, Va., and told police March 19 that he was partying at a club at the Power Plant Live! complex the night before. The man told police that he woke up in his Mount Vernon hotel room with a black eye and scrapes and bruises all over his body. His Tag Heuer watch was missing, as well as an iPhone and the keys to his Audi.

At the time, he told police he couldn't remember what had happened or where. With the attention the video received, police have connected the dots, Moses said. Police did not release the victim's name.

Even by Internet standards, where the wildest videos get the most views, the video is shocking for its humiliation and brutality. The victim seems disoriented and is punched after he apparently tries to get back something taken from his pocket.

But something happened when the video hit Twitter: Most people were not impressed. An influential Twitter user from Baltimore who has 47,000 followers posted it and wrote, "Black Power. LMAO," an abbreviation for laughing. He included the Twitter account of the man who allegedly threw the punch.

Friends and strangers then started taking him to task. "That ... wasn't even funny. Come on now," one person wrote. "That's so ... wrong. You shouldn't even wanna admit to being in it," another said.

A man who said he threw the punch wrote back, defending himself by saying it was in self-defense.

By that time, the video had aired on television and caught fire on message boards, where insomniac posters from beyond the Baltimore area began diving into social media to determine who posted the video and who threw the punch. Soon, screenshots of a Facebook page were being matched to stills from the video and accompanied by other identifying information.

Attempts by The Baltimore Sun to reach the man were unsuccessful. Police say the investigation is continuing.

Baltimore Sun reporter Peter Hermann contributed to this article.

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