The body of 81-year-old Gewynn Leigh Taylor was found in a car with husband George Leigh Taylor on Dec. 10.
He told a Montana de Oro State Park ranger the couple was depressed and they had a suicide pact. But he failed to kill himself despite slashing his wrists and neck and trying to suffocate himself.
The retired firefighter was initially charged with murder, but San Luis Obispo County prosecutors reduced it to assisted suicide.
The Tribune of San Luis Obispo ( http://bit.ly/TC93TY) says Taylor pleaded guilty on Wednesday.
He's free until sentencing next month. It's unclear if he's facing jail time.
Information from: The Tribune, http://www.sanluisobispo.com