Investigators would not reveal what new evidence led them to suspect the boy's father, but they believe Andressian senior killed his son in the early morning hours of April 21 after the boy left Disneyland. The father's attorney called the disappearance a mystery and has said his client had gaps in his memory.
Helicopters and dive teams were deployed to Lake Cachuma, an artificial lake about 15 miles northwest of Santa Barbara, after Andressian said he traveled there with his son.
The suspect was booked at the Clark County Detention Center with a bail of $10 million and will return to Los Angeles County pending the extradition process.
There have been no official sightings of Andressian Jr. since he was seen on Disneyland cameras with his father in April.More news: Home sales up in May, but buyers face sharply rising prices
Lacey said that while "no-body cases" present a challenge for prosecutors, her office has successfully obtained convictions in many such cases.
Investigators have said that Andressian had provided authorities with "inconsistent" and "misleading" statements. He told authorities he'd taken prescription pills, and the auto had been doused in gasoline.
The same day the child was reported missing, Andressian Sr., was found unconscious near his vehicle, which was parked at the Arroyo Seco Park in South Pasadena. The arrest was made by officials with the Los Angeles County Sheriff's Department, the Las Vegas police and the U.S. Marshals Service. Jackie Lacey said her office has successfully prosecuted murder cases without a body and that she was confident there was strong evidence that Andressian "committed this awful crime".
Further details were not provided and weren't expected until Monday morning, police said.More news: Fed: Biggest US banks strong enough to withstand recession
Andressian was initially arrested in mid-April on charges of child endangerment and child abduction after he was found unconscious in South Pasadena's Arroyo Park with his son, Aramazd Andressian Jr. nowhere to be found. He was released after investigators decided not to move forward with charges.
Aramazd Andressian Sr. was taken into custody Friday in Las Vegas.
Estevez has also spoken publicly, pleading for the public's help at a May news conference with law enforcement. Before their statements Monday, sheriff's officials had said witnesses reported seeing the boy with his father there.
"My heart is shattered and I will miss my son immensely each and every second of every day for the rest of my life", she said in the statement. She said her estranged husband had failed to drop off the child at a pre-arranged meeting place. She expressed great sorrow at the conclusion that her son is nearly certainly dead. "Piqui was everything great in my life and I can not imagine the emptiness and the void that I will bear until we are together again one day", the statement said.More news: How will Amazon transform Whole Foods? (The 3:59, Ep. 242)
Anyone with information on the case is asked to contact the sheriff's Homicide Bureau at 323-890-5500.