The killer of a California police officer has died after being found unresponsive in his cell at San Quentin State Prison.
Corrections officials say 35-year-old Miguel Magallon died Saturday despite emergency measures, and an autopsy will be conducted.
Magallon was sentenced to death on Oct. 15, 2009, for the 2004 murder of Capt. Michael Sparkes Sr. of the Los Angeles County Office of Public Safety.
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Sparkes was taking his regular early morning bike ride in a neighborhood near his Compton home when Magallon approached on foot to rob him and shot Sparkes multiple times before fleeing to a waiting car.
Prosecutors say Sparkes was able to call 911 but Magallon returned with another man and fatally shot Sparkes.
Getaway driver Orvis Camillo Anthony was sentenced to 50 years to life.