SAN JUAN, Puerto Rico (Reuters) - Former three-time world boxing champion Hector "Macho" Camacho is brain dead following a drive-by shooting in Puerto Rico, a doctor said on Thursday.

Relatives are expected to decide on Thursday whether to remove Camacho, 50, from life support, said Dr. Ernesto Torres, director of the Rio Piedras Medical Center in Puerto Rico.

Camacho "is clinically brain dead," Torres told reporters. "We have done all we can do."

Camacho was shot in the neck and face late on Tuesday when he sat in a parked car in Bayamon, a San Juan suburb. The driver was killed, and police have no motive for the shooting.

Camacho was hit in the jaw by a bullet that fractured two vertebrae and lodged in his shoulder.

Torres said Camacho was in a deep coma and unresponsive. Brain studies taken overnight were negative and the results were taken to a neurologist for a final determination.

Camacho's mother, Maria Matias, and other relatives were going to be updated about the former boxer's condition, Torres said.

(Reporting by Reuters in San Juan, Writing by Ian Simpson, Editing by Stacey Joyce)