UFC heavyweight Shane del Rosario’s death was due to natural causes, according to medical examiners.

A death certificate issued Wednesday by the Orange County (Calif.) coroner’s office said the 30-year-old fighter suffered brain damage from a lack of oxygen to the brain, an abnormal heart rhythm commonly associated with heart attacks and a congenital heart disorder.

The immediate causes of death were listed as anoxic encephalopathy, ventricular fibrillation and Long QT Syndrome. But the death certificate also listed “other significant conditions contributing to death but not resulting in the underlying cause;” namely cocaine, opiates and THC were present in the fighter’s body.

O.C. Supervising Deputy Coroner Daniel Aikin told MMAjunkie that the drugs were found as part of a routine urine screen by the hospital. The amount of drugs is unknown because an autopsy wasn’t performed.

Del Rosario spent nearly two weeks at Hoag Memorial Presbyterian Hospital in Newport Beach, Calif. The UFC said he suffered a heart attack on Nov. 26 and announced his death on Dec. 9. The fighter was declared dead, however, six days earlier – at 4:40 p.m. PT Dec. 3, according to his death certificate.

“What we go by is when a neurologist pronounces them brain-dead, when they get a second brain-dead pronouncement,” Aikin said. “The family was not allowing the hospital to remove him from life support.”

Del Rosario’s manager Jason House has said previously the Del Rosario family was interested in starting a charitable foundation to research Long QT Syndrome, an inherited condition which can strike young people and lead to sudden cardiac arrest due to ventricular fibrillation.

House had no comment Friday on the death certificate findings, and trainer Colin Oyama did not immediately respond to a request for comment.

Del Rosario was found unconscious Nov. 26 by his roommate, UFC flyweight Ian McCall. Del Rosario’s sudden passing came as a shock to the MMA community.

On Nov. 21, five days before his heart attack, Del Rosario withdrew from a fight with Guto Inocente at UFC 168 when he suffered a rib injury.

Del Rosario (11-2 MMA, 0-2 UFC) got his start in MMA in 2006 after fighting in kickboxing and muay Thai. He went 11-0 as a professional and then signed with Strikeforce, where he earned first-round stoppage wins over Lolohea Mahe and Lavar Johnson.

A June 2011 fight with Daniel Cormier was scrapped after he suffered a herniated disc in his back when a drunk driver rammed his car. He didn’t fight again until his UFC debut, which he lost via second-round TKO. After a subsequent loss to Pat Parry, he withdrew from bookings against Dave Herman and Inocente due to injury.