(CNN) -- The San Diego Medical Examiner's Office on Wednesday ruled as a homicide the death of Mexican man who was beaten and tasered while in the custody of U.S. border agents.
Anastasio Hernandez Rojas died of cardiac arrest, an autopsy found, but methamphetamine abuse and hypertension were also contributing factors.
The Mexican government said the autopsy results "support the strong condemnation the government of Mexico made from the outset, publicly demanding through diplomatic channels a thorough and impartial investigation."
Mexico has asked for an explanation about what happened to Hernandez while he was in U.S. custody.
The altercation occurred Friday night at the San Ysidro Port of Entry when U.S Customs and Border Protection agents were trying to deport Hernandez to Mexico, San Diego and federal authorities said. Hernandez became combative, the officials said, and force was used to restrain him.
"One of the agents used a baton to administer to the subject to get him to stop fighting," said San Diego homicide Capt. Jim Collins. "When that was not successful, they used the Taser."
Hernandez stopped breathing shortly after being tasered, San Diego police said in a statement Saturday.
Notimex, the Mexican government-run news agency, said the man was brain dead and doctors proposed disconnecting him from life-support.
He died Monday afternoon at Sharp Chula Vista Medical Center in Chula Vista, California, a hospital spokeswoman and police said.
CNN's Nick Valencia contributed to this report.