The McStay family vanished without a trace in 2010. Their remains were discovered last week and San Bernardino County Sheriff's officials said the family had been killed.
For four years, police have had few leads on what happened to the family of four, who left their Fallbrook home one February night and were never heard from again. Their car turned up near the Mexican border.
Authorities are treating the deaths as homicides.
Speaking to the Daily Mail this week, Merritt said he decided to tell his story now -- after years of silence -- because he wants to help find the family's killer.
On Monday, Joseph McStay's father said in an interview with HLN's Nancy Grace that he has identified several possible suspects in the killings.