The San Bernardino County Sheriff’s Department is investigating the death of Christian Siqueiros, who died in police custody on Thursday, NBC Los Angeles reports. Siqueiros was arrested after the Montclair Police Department received a disturbance report from someone in his former apartment building.

Montclair police said Siqueiros “became combative” when they arrived at the apartment building, out of which he had recently moved, and to which he had briefly returned, NBC reports, on Thursday. He went into cardiac arrest while in custody and died at a hospital.

According to his sister Maria, Siqueiros—who would have turned 26 on Monday—was in good health. One neighbor, who witnessed the arrest, told NBC Los Angeles that she saw between five and eight officers taking Christian down, sitting on him, and tying his legs together.

“They don’t need 20, 30, 10 cops to be on top of the guy just to stop him,” Maria Siqueiros said. “I just want to know the truth so we can be at peace.”

Image via NBC. Contact the author of this post: brendan.oconnor@gawker.com.