A sex offender was convicted Thursday of murdering four Orange County prostitutes in a case that was cracked in part by the GPS monitor he was wearing during the killings as a result of his earlier felony conviction.

Steven Dean Gordon, 47, acted as his own attorney at his trial, admitting his involvement in most of the abduction murders, although he insisted his co-defendant, 30-year-old Franc Cano, was the main culprit in hunting down and killing the four victims. Cano is awaiting trial.

Gordon's case will now shift to penalty phase, during which jurors will recommend either the death penalty or life in prison without parole.