Shortly after earning one of the fastest four-chair turns in the history of NBC's The Voice, Philadelphia street performer Anthony Riley has left the show.

Coach Pharrell Williams made the announcement on Monday night's episode, saying that Riley would not be returning for "personal reasons." As a result, The Voice saw its first ever three-way knockout round.

With such a vague reason given for the sudden departure of a crowd favorite, the Internet rumor mill naturally went wild following last night's episode. NBC, however, has declined to comment further on Riley's reasons for leaving.

On the gossip side of the Web, several sites suggest that Riley left the show over his refusal to sing in The Voice's Knockout rounds against fellow crowd favorite and Pittsburgh native Mia Z. Which, of course, appears to be little more than gossip.

The more conspiracy-minded side of the Internet, for its part, points to a tweet Riley posted from March 10 that showed his support for Mumia Abu-Jamal. In it, he dedicates his Battle Round from that week to the highly controversial political figure:

Logically, however, Riley's departure seems to go back to those "personal reasons" Pharrell alluded to and NBC echoed in response for comment. Jett Prescott, a person claiming to be Riley's friend, as Yahoo Music notes, even said the same via Twitter last night:

Until this morning, Riley himself did not have any social media activity since March 17, and requests for comment from him have gone unanswered. So, for now, we can't be sure exactly why Riley departed from the show, save for those "personal reasons" Pharrell touted Monday night.

Whatever the cause, though, he certainly had a good run. Below, check out Anthony slay James Brown's "I Got You (I Feel Good)" from his initial audition for The Voice: