The father of a 5-year-old Pasadena boy missing since April arrived back in Southern California Friday after being extradited from Las Vegas to face a murder charge.

As for a motive, investigators would only say they believe it stemmed from a divorce dispute and custody battle with the boy's mother. Authorities said Monday the divorce was part of the criminal investigation, NBC Los Angeles reported.

Court documents show that the father made allegations that the boy was being sexually abused by the son of the mother's boyfriend. Both police and the Los Angeles County Department of Children and Family Services became involved, but no evidence of abuse was found. 

Police were never able to identify either a boyfriend or his child, the documents show. 

It was reported earlier that Aramazd Andressian Sr. tried to commit suicide and was getting ready to flee the US to a country from which he could not be extradited.

Boy’s mother reported him missing on April 22, after his father, with whom she shares custody, failed to show up to their arranged meeting point to drop off their son.

Aramazd Andressian Sr. was found unresponsive in Arroyo Park early morning on April 22, a short distance from his vehicle. The toddler, however, was not with his father at that time.