Authorities have kept quiet for months about what drove them to charge a California man with killing a family of four and burying their bodies in shallow desert graves north of Los Angeles.
But San Bernardino prosecutors on Monday finally revealed the chilling details of the murders and the case they've been building against 58-year-old welder Charles "Chase" Merritt, who is accused of killing his business partner, Joseph McStay, the man's wife, Summer McStay, and their two young sons, Gianni McStay and Joseph Mateo McStay.
Merritt, who was arrested last November, has pleaded not guilty to quadruple murder.
Prosecutors said in court Joseph McStay's body was found in a shallow grave 100 miles from the family home in Fallbrook with an extension cord wrapped around his neck and a blanket wrapped around him. He was beaten and killed along with his wife, Summer McStay, who had "multiple bone fractures to the head" and died of blunt force trauma to the head.
Four-year-old Gianni McStay, the couple's older son, had at least seven blunt force wounds to the head.
A detective who testified in court said 45 bones, at least two of which were from children, were found at the graves, along with the entire body and skull of a child and clothing.
A three-pound sledgehammer was also found in one of the two graves, along with other items. A medical examiner said at least three of the four family members were likely killed with the sledgehammer.
A detective said tire tracks from a "large vehicle" were found near the graves and an FBI agent said they connected calls made in the area where the bodies were found to Merritt's phone.
The McStay family vanished on Feb. 4, 2010, puzzling investigators who said there were no signs of forced entry at the home, nothing was missing, and the couple's credit cards and tens of thousands of dollars in bank accounts were untouched. Joseph McStay's brother found that there was food left on the kitchen counters and the family dogs were unfed when he went to check on them after Joseph stopped answering his cell phone.
The disappearance received national attention and there was speculation that the family was in Mexico, after computer records showed searches for travel to Mexico and children's passports and investigators received a tip that they had been spotted in El Rosario. More than three years later, in November 2013, the family's remains were found in Victorville, California.
Merritt's lawyer, Jimmy Mettias, said he expected prosecutors to allege his client used a sledgehammer to kill the McStays after a business dispute and covered up his tracks by painting the family's house and burying his victims and the weapon in the desert.
Merritt served as his own attorney in February, saying he only had six to eight months to live because of congestive heart failure and could not afford an attorney.
Mettias said nothing on the sledgehammer could be traced to Merritt, and questioned prosecutors' ability to link his client to the crimes.
"We have serious issues with the state of the evidence," he said. "I could see where they chose, OK, we're going to go with this guy, but nothing that is going to prove his guilt."
Mettias said he expected prosecutors would say Merritt took money from McStay's business building indoor water features, prompting a confrontation between the men.
Mettias said his client had an alibi, but he would not reveal it before trial.
NBC San Diego's Samantha Tatro and Paul Kreuger contributed to this report.