District Attorney Mike Ramos filed notice Monday in San Bernardino County Superior Court in the case against Charles "Chase" Merritt.
Prosecutors say Merritt killed his former business associate, Joseph McStay, Mc Stay's wife Summer, and their two children, 4-year-old Gianni and 3-year-old Joseph Jr. on Feb. 4, 2010.
The cause of death was blunt force trauma to the head. There were at least four impacts to the skull of Joseph McStay, and at least seven impacts to Gianni.
The skeletal remains of Joseph McStay were found with a cutoff extension cord wrapped around the neck, and the rest of the body wrapped in a white towel, all of it secured by a tie-down strap.
Merritt, who's being held without bail, has maintained his innocence. Search warrants served in the case will be unsealed Wednesday.
Merritt is scheduled for trial on Aug. 10.