Pimp C, one half of the legendary hip-hop duo UGK, was found dead today in his hotel room bed. He was 33.

The rapper, whose real name was Chad Butler, was staying at the Mondrian Hotel in West Hollywood when he died of unknown causes. An investigation by Los Angeles County Sheriff’s Department’s homicide unit is currently underway.

The Texas rap pioneer’s mom said he’d been working on a collaboration with Three 6 Mafia.

“He was in L.A., doing what he loved most,” she said.

Earlier this year, UGK’s last album, Underground Kingz, debuted at #1 on the Billboard albums chart and sported the hit track “International Players Anthem” featuring Outkast.