MODESTO  (AP) — Modesto police say they have arrested on suspicion of murder the son of a couple whose bodies were found in their burning home.

Police told said that 25-year-old Brandon Pettit also is being held on suspicion of arson and conspiracy in the Aug. 8 deaths of David Scott Pettit and Janet Pettit. Also on Saturday police arrested 26-year-old Felix Valverde in connection with the case.

Police said the Pettits were dead before the house caught fire. They have not said how the couple died.

Janet Pettit was a neonatal nurse practitioner at Doctors Medical Center. Scott Pettit owned a martial arts school and was the city of Riverbank’s citizen of the year in 2007.

Police say the investigation is ongoing. They declined to release more information.