SAN DIEGO (AP) - An autopsy finds a man who was shot with a stun gun by U.S. immigration authorities at a San Diego border crossing died of cardiac arrest.

The San Diego County Medical Examiner's Office says in a report released Tuesday that 40-year-old Francisco Manuel Cesena's cardiac arrest occurred because he was shot and held face down on the ground and he was under the influence of methamphetamine and heroin. The manner of death is ruled a homicide.

The report says the resident of suburban El Cajon became combative when he returned from Mexico at the San Ysidro port of entry Dec. 24 and was told he was being arrested. He was wanted on a felony arrest warrant.

Customs and Border Protection had no immediate comment on the status of its internal investigation.

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