The Los Angeles County Sheriff's Department did not say what specifically led to Aramazd Andressian Sr.'s arrest.
"After reviewing all of the evidence in this case, Homicide Investigators presented the facts to the Los Angeles County District Attorney’s Office and obtained a murder filling against the suspect," the Sheriff's Department said in a release posted to Facebook.
His 5-year-old son was last seen in the early morning hours of Friday, April 21. Andressian Jr. was in the custody of his father at the time. The boy's mother reported that Andressian Sr. did not bring their son back during a planned custody exchange, CNN reported.
Police found Andressian Sr. in a hospital the next day, according to CNN. Andressian Sr. said he took prescription medication that was not prescribed to him that morning and that he did not remember what happened to his son.
The boy is still considered missing. Andressian Sr. is being held on $10 million bail.