ANAHEIM, Calif. (AP) — A police chief in California says two parolees charged with killing four women were wearing GPS trackers at the time of the murders — and there may be more victims.

Anaheim Chief Raul Quezada said Monday that Franc Cano and Steven Dean Gordon were both wearing the ankle monitors last fall when the women were killed in Anaheim and Santa Ana.

Cano and Gordon are registered sex offenders who have known each other since at least 2012.

They were charged Monday with four counts of murder and four counts of rape and could face the death penalty if convicted.