Updated

Investigators suspect the father of a 5-year-old California boy who has been missing for two months killed the child after a family outing at Disneyland in a plot to get back at his estranged wife during a bitter separation, Los Angeles County sheriff's officials said Monday.

The body of Aramazd Andressian Jr. has not been found and investigators would not release specific details of what led to the filing of the murder charge, but said there is strong circumstantial evidence in the case to prove the boy was killed by his father, Aramazd Andressian Sr.

"I am confident the evidence proves Mr. Andressian committed this horrible crime," Los Angeles County District Attorney Jackie Lacey said.

Investigators have been searching for the missing boy since his father was found passed out in a large park in South Pasadena on April 22. Sheriff's officials say the father had taken prescription pills and was found in a car doused in gasoline in what they say was an attempt to take his own life.

The boy was last seen leaving Disneyland with his father around 1 a.m. on April 21. Investigators believe Andressian killed his son a short time later and then drove about 145 miles (230 kilometers) later that morning to Lake Cachuma in Santa Barbara County. Sheriff's homicide detectives have searched the lake twice in the past few months, using dogs and a dive team to help in the search.

Andressian, 35, was arrested Friday by sheriff's homicide detectives and federal agents in Las Vegas because he was "becoming a flight risk," Los Angeles County Sheriff Jim McDonnell said. He's being held there on $10 million bail.

Andressian changed his appearance and had been socializing while living out of a Las Vegas hotel for 47 days, conduct characterized as inconsistent with that of a grieving parent, said sheriff's Lt. Joe Mendoza. Investigators also believe Andressian was planning to leave the U.S. and flee to a country that does not have an extradition agreement with the U.S., Mendoza said. Officials declined to identify the country.

Detectives believe Andressian killed his son in an attempt to get back at his estranged wife for their "tumultuous" relationship, Mendoza said.

Andressian's attorney, Daniel Nardoni, has said his client "is adamant that he never harmed his son Aramazd and is innocent of the charges." Nardoni did not immediately respond Monday to an emailed request for comment.

Andressian is expected to appear in court in Las Vegas on Tuesday for an extradition hearing and will likely be brought back to Los Angeles by the end of the week, prosecutors said.

"My heart is shattered and I will miss my son immensely each and every second of every day for the rest of my life," the boy's mother, Ana Estevez, said in a statement released by the sheriff's department.

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