People typically may feel relief to learn of an arrest in a family member's death, but Patrick McStay, whose son, daughter-in-law and two young grandchildren were killed in 2010, instead felt a crushing weight.
"A lot of people will say it's like lifting a ton off your shoulders. I said, no, it was more to me like a boulder falling on me," McStay told CNN Monday.
In an interview with CNN's Randi Kaye that aired Monday night, McStay said he's uncertain whether his son's business partner, Charles "Chase" Merritt, was capable of killing the family.
"I still can't say yes, but I can say I still wonder," McStay said.
Last week, four years after Joseph McStay, his wife, Summer, and their two sons -- Joseph Jr., 3, and Gianni, 4 -- mysteriously vanished from their Fallbrook, Calif., home, authorities arrested Merritt and charged him with four counts of murder.
The arrest came roughly one year after the family's remains were found in a remote patch of desert off the 15 Freeway in Victorville. Coroner officials determined the McStays died of blunt-force trauma.
Charges were filed against Merritt in San Bernardino County because that's where the remains were found, officials said.
Speaking to reporters after the arrest was announced last week, Dist. Atty. Mike Ramos said Merritt will be eligible for the death penalty if convicted.
"I don't need to tell you this is a cold and callous murder on an entire family," Ramos said.
Merritt's arrest also comes nearly a year after he gave an interview to the British tabloid Daily Mail in which he said he spent more than an hour with Joseph McStay the day he and his family went missing from their suburban San Diego County home.
Merritt, who said he was the last person Joseph McStay called from his cellphone before disappearing, claimed he did not know anything that could help solve the crime.
He said he was questioned by police and submitted to a polygraph examination.
The two worked together as part of McStay's custom fountain business.