South Pasadena father pleads guilty to killing 5-year-old son

ALHAMBRA, Calif. -- After long maintaining his innocence, a South Pasadena father pleaded guilty of murdering his 5-year-old son.

RELATED: Father in Southern California allegedly killed boy to get back at ex-wife

Aramazd Andressian Sr. pleaded guilty to first-degree murder in an Alhambra courtroom Tuesday morning.

The body of Aramazd Andressian Jr. was found near Lake Cachuma in Santa Barbara County in June.

The boy was last seen April 21, leaving Disneyland with his father, grandmother and aunt.

A day later, Andressian Sr.'s estranged wife Ana Estevez reported her son missing after the father did not drop the boy off as scheduled.

Andressian Sr. was found passed out in his car at Arroyo Seco Park in South Pasadena, and the child was nowhere to be found. Andressian Sr. was unable to account for his son's whereabouts.

RELATED: Body of boy reported missing in SoCal found near Lake Cachuma

Authorities initially arrested Andressian Sr. in Los Angeles after his son's disappearance, but he was released due to lack of evidence.

Following extensive investigation, Andressian Sr. was arrested again in Las Vegas on June 23.

RELATED: Father arrested for murder of son who went missing in SoCal 2 months ago

Andressian Sr. initially pleaded not guilty to a murder charge, but changed his plea Tuesday.

Authorities believe the motive for the killing was revenge on Estevez. Court documents detail a stormy relationship between the two, and allegations flew back and forth about the treatment of their son.

Andressian Sr. could be sentenced to 25 years to life behind bars. He is currently being held on $10 million bail.