CHICAGO — Four black people were charged with hate crimes Thursday in connection with a video broadcast live on Facebook that showed a mentally disabled white man being beaten and taunted, threatened with a knife and forced to drink from a toilet.

The assault went on for hours, until Chicago police found the disoriented victim walking along a street, authorities said.

The suspects, who were jailed, can be heard on the video using profanities against white people and President-elect Donald Trump.

Police spokesman Anthony Guglielmi said investigators initially concluded that the 18-year-old man was singled out because he has “special needs,” not because he was white. But authorities later said the charges resulted from both the suspects’ use of racial slurs and their references to the victim’s disability.

It’s also possible that the suspects were trying to extort something from the victim’s family, police said. The man’s parents reported their son missing Monday and told authorities they later received text messages from people who claimed to be holding him captive.

The victim was a classmate of one of the attackers and initially went with that person voluntarily, police said.

Excerpts of the video posted by Chicago media outlets show the victim with his mouth taped shut and slumped in a corner of a room. At least two assailants are seen cutting off his sweat shirt, and others taunt him off camera.