Police believe he killed the boy in an act of revenge against the boy's mother.
A devastated mom revealed her sorrow while issuing a rebuke of her ex-husband as he was sentenced for killing their son after a trip to Disneyland earlier this year.
Read: Parents Charged in 2-Year-Old Son's Suffocation Death
Ana Estevez broke down in tears as she remembered her son, Aramazd Andressian Jr., while addressing a Los Angeles courtroom Wednesday.
“My son had an immense heart and loved life," she said. "Because of this selfless heinous crime, I will forever be deprived of the joys that come along with being a mother."
The murdered 5-year-old’s grieving mom came face-to-face with her ex in a packed and tense courtroom. There was so much concern that emotions would spill over that 13 court officers were on hand to keep things under control.
Authorities say Aramazd Andressian Sr. killed his son because he wanted to get back at his estranged wife. The boy was last seen leaving Disneyland with his father in April.
On the day his son was reported missing, Andressian was found passed out in a car that had been doused with gasoline in what authorities say was a failed suicide attempt.
He claimed he didn't know what had happened to the boy and was released.
Andressian later took off to Las Vegas, where authorities discovered he had dyed his hair and shaved off his beard. He was arrested in June.
He showed no remorse at his first court hearing in Vegas and even laughed and joked about being extradited back to California.
“If California wants me, they can come get me,” he said earlier this summer.
He later told investigators where the boy's body would be, at a lake in Santa Barbara County.
On the day of his funeral, the boy's devastated mom carried her son's hat to his tiny coffin.
Watch: Child Found Preserved in Coffin From 1800s Gets Headstone With Her Real Name
“I find myself living with an eternal shadow and devastation and emptiness because I don’t have you here with me,” she said at his funeral.
At Wednesday’s sentencing, Estevez had a pointed message for the killer.
“I pity you," she said. "You are a failure as a father. You are a failure as a human being."
He was sentenced to 25 years to life behind bars.
Watch: Friend Raises Incredible $200,000 in Memory of Woman Killed in Charlottesville Attack
