The trial of a man accused of torturing his girlfriend's 8-year-old son to death opened Monday in a Los Angeles courtroom.

According to KTLA, a Los Angeles County District Attorney's Office prosecutor told jurors that Isauro Aguirre killed Gabriel Fernandez because he thought he was gay.

Aguirre, 32, and his girlfriend Pearl Fernandez, who also faces trial, have pleaded not guilty to charges of capital murder and a special circumstance of torture.

On May 22, 2013, Pearl Fernandez called 911 to report that Gabriel was not breathing. Authorities found the boy naked in a bedroom, his skull cracked, three ribs broken and BB pellets embedded in his lung and groin. He died from his injuries two days later in a hospital.

Prosecutor Jon Hatami said that the couple called 911 in an attempt to mislead authorities.

“They didn't call 911 to help Gabriel. They called 911 to cover up what they did. The defendant lied on the 911 call,” Hatami said.

He added that Aguirre made Gabriel go to school dressed up in girls' clothes, and pointed out that Aguirre towered over Gabriel at six-foot-two and 270 pounds.

Defense attorney John Allan said that his client did not intend to “kill Gabriel with the infliction of torture.”

“Despite the horrific abuse, Isauro never intended for Gabriel to die,” he said.

Hatami said that text messages between Aguirre and the boy's mother prove that they conspired to torture and kill Gabriel.