Ana Estevez sat in the front row of an Alhambra courtroom, clutching a small white urn that held the remains of her 5-year-old son.

Within moments, the man just a few feet in front of her would plead guilty to the boy’s killing.

This was no stranger. It was the man she had once loved, the father of their child.

Estevez and her family and friends wept Tuesday as a prosecutor read aloud the murder charge and mentioned the victim by name: Aramazd Andressian Jr.

Wearing yellow jail scrubs, his father, Aramazd Andressian Sr., pleaded guilty and answered “yes” to questions about whether he understood his rights and the consequences of his decision to change his plea. Andressian was barely audible, prompting Superior Court Judge Cathryn F. Brougham to ask him to speak up.

Before he was escorted from the courtroom, Andressian turned and glanced at his estranged wife and her family. He is scheduled to be sentenced to 25 years to life in prison when he returns to court Aug. 23.

The boy’s disappearance in April after leaving Disneyland with his father and two other relatives led to a frantic search that dragged on for more than two months and culminated in the discovery of the child’s remains June 30 near Cachuma Lake in Santa Barbara County.

Outside the courthouse Tuesday, Deputy Dist. Atty. Craig Hum called the killing “horribly tragic.”

“Every murder is a tragedy, but cases like this really, really tug at your heart,” he said.

The boy’s family did not speak to reporters after the hearing.

Andressian’s attorney said his client had not planned the killing and was now taking responsibility for the “awful crime.” Andressian had told authorities where to find his son’s body, which led to the discovery of the remains, attorney Ambrosio Rodriguez said.

“He is beyond words in regretting having committed such an act,” Rodriguez told reporters.

Andressian was accused of planning the killing to get back at his estranged wife during tumultuous divorce proceedings that began in April 2016.

In court records, Andressian alleged that Estevez spanked their son, used profanity and talked of taking the boy to Cuba. He said he was concerned that Estevez’s father practiced the religion of Santeria and once sacrificed a rooster in front of the child.

In 2016, Andressian made allegations that the child had been sexually abused by “Omar,” the son of Estevez’s new boyfriend, “TJ,” according to the court documents. Estevez told police at the time that she did not have a boyfriend, and that her child never complained of abuse. After a social worker questioned the child about the allegations, the child admitted to not telling the truth and said his father told him to lie, according to court records.

Estevez, an elementary school principal, accused her husband of falsely saying he was a stay-at-home dad who was their son’s primary caregiver, the records show. She said her mother and father took care of Aramazd Jr. when she was at work, she said.

She alleged that her husband had a gambling problem and was addicted to prescription drugs, according to the court documents. She said he told her that if anything were to happen between them, he would take the child to Iran or Armenia.

A Los Angeles County judge ordered Estevez to pay her husband spousal and child support because he wasn’t working. Both parents were awarded joint custody of their son.

The boy was last seen alive about 1 a.m. April 21 as he was leaving Disneyland with his father, aunt and grandmother. Estevez reported him missing the next day, after Andressian failed to show up at a planned custody exchange.

Andressian was found unconscious in a South Pasadena park, his gray BMW doused with gasoline, and said he didn’t know what had happened to his son. Authorities said he had tried to kill himself by taking prescription pills that were not his.

Andressian initially was detained, then released because of a lack of evidence. He told Los Angeles County sheriff’s detectives that he had gone with his son to Cachuma Lake Recreation Area in Santa Barbara County.

As the search for her son continued, Estevez filed paperwork asking the divorce court to end the child and spousal support payments. Her husband, she declared, had “lost our son while our son was in his custody.”

She said she had provided “hard evidence showing” Andressian’s character, “yet my evidence was ignored,” she wrote. At the same time, she said, her husband’s statements “with no supporting documents was believed and relied upon by this court.”

The detectives found evidence that Andressian was at the lake on the day the boy went missing, but there were no sightings of his son.

Authorities suspect the child had been killed shortly after leaving Disneyland, before the father went to the lake.

Andressian was arrested June 23 in Las Vegas, where he had stayed on and off since his son’s disappearance. Investigators said he had lightened his hair, shaved his beard and appeared to be making plans to travel to a country where he could avoid extradition.

Authorities discovered the child’s remains the same day Andressian was flown back to California. Detectives have not released a cause of death.

nicole.santacruz@latimes.com