An El Cajon man who died in the custody of Customs and Border Protection employees on Christmas Eve, died of cardiac arrest according to a medical examiner's report.
Francisco Manuel Cesena, 40, died because he was shot and held face down on the ground, officials said.
Cesena was also under the influence of methamphetamine and heroin according to the San Diego County Medical Examiner's Office report released Tuesday.
The manner of death is ruled a homicide.
On December 24, 2014, Cesena was walking through the San Ysidro Port of Entry in south San Diego when officers recognized him as being armed and dangerous.
After detaining and patting him down, authorities allegedly found heroine on Cesena and later discovered he was wanted on a felony warrant.
Following his detainment, Cesena allegedly attacked two officers. To control him, officers used a Taser on him.
He became unresponsive and was pronounced dead less than an hour later at Sharp Chula Vista Hospital.
Officers said in a statement they only had the intent to arrest the suspect, not to kill him.
Customs and Border Protection had no immediate comment on the status of its internal investigation, the Associated Press reported.