Aramazd Andressian, 35, pleaded guilty earlier this month to first-degree murder in the death of his son, Aramazd Andressian, Jr.
Several of the child's family members, including his mother Ana Estevez, delivered emotional statements in court.
"I wish that I was taken instead of my son, so that my sweet baby can live," she cried. "I will never see my son fall in love and marry the woman of his dreams. He was my greatest happiness and is now my greatest sadness."
The boy was last seen April 21, leaving Disneyland with his father, grandmother and aunt.
A day later, Andressian's estranged wife 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, with the child was nowhere to be found. He was not able to account for his son's whereabouts.
During her emotional statement, Estevez told her estranged husband she pities him.
"You are a failure as a father, you are a failure as a man and you are a failure as a human being," she said. "Your cowardice behavior is inexcusable and appalling."
In response to the statements, Andressian's attorney spoke on behalf of his client.
"There are no words to, obviously, justify what happened," the attorney said. "My client eventually did do the right thing and confessed."
Andressian Sr. initially denied being involved in the murder, but he later confessed and led investigators to the little boy's body near Lake Cachuma