FULLERTON (CBS) — A 37-year-old Fullerton police officer pleaded not guilty Monday morning to homicide charges in the death of a schizophrenic homeless man.

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A judge also rejected Officer Manuel Ramos’ bid to lower his $1 million bail.

Ramos was charged last week with second-degree murder and involuntary manslaughter in the death of Kelly Thomas, 37, who died after a violent confrontation with six officers responding to reports of car burglaries at the Fullerton Transportation Center on July 5.

KNX 1070’s Jon Baird reports.

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Orange County District Attorney Tony Rackauckas announced the felony charges Thursday. The other four officers involved in Thomas’s arrest will not face criminal charges. All six officers are on administrative leave.

Ramos turned himself in after the charges were announced and appeared in a downtown Santa Ana courtroom that afternoon.

Orange County Superior Court Judge Erick Larsh set bail at $1 million for Ramos and ordered him to surrender his

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Rackauckas said Ramos, a 10-year Fullerton Police Department veteran, faces up to 15 years to life in prison if convicted.