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Josh Acosta, left, and Frank Felix are shown in booking photos released Sept. 25, 2016, by the Fullerton Police Department.

A former Army mechanic was sentenced to life in prison without the possibility of parole for the shotgun slayings of a Fullerton couple and their friend in 2016, officials announced Friday.

Last month, Joshua Charles Acosta, 23, was found guilty of three counts of murder, along with the special circumstance of multiple murders and the special allegation that he personally used a gun in the crime.

Acosta’s codefendant, Frank Sato Felix, 27, of Sun Valley, is scheduled for a pre-trial hearing on Feb 1.

Prosecutors said Acosta entered the home of  Christopher Yost and Jennifer Goodwill Yost — where Arthur William Boucher was also staying — on Sept. 24, 2016.

Acosta shot Boucher as he slept on the living room couch, then went to the master bedroom where he shot Goodwill Yost in the face, prosecutors said. The defendant then shot Yost in the head after he woke up and tried to run away.

The couple’s children were home during the incident and discovered the bodies later that morning, officials said.

Victims Christopher Yost and Jennifer Goodwill Yost, left, and Arthur William Boucher are shown in family photos released Sept. 25, 2016.

Acosta was arrested at his Army barracks in Fort Irwin, and Felix was eventually arrested at his Sun Valley home, according to the Fullerton Police Department.

Goodwill Yost’s daughter, Katlynn Goodwill, who was 17 at the time of the killings, testified that she had planned to run away with help from Acosta and Felix, but did not know the defendants planned violence, according to the Orange County Register.

The teen testified that Yost, who was her stepfather, had molested her for more than a decade and that she told Felix about the abuse, the newspaper reported.

Though Goodwill’s parents had told her to stay away from Felix, she testified that Felix had blackmailed her into having sex with him by threatening to reveal the sexual abuse to her mother.

The teen testified that she planned to tell her mother about the abuse and leave home the night the killings occurred. She added that she had second thoughts, but felt pressured by Acosta to move forward with the plan, according to the newspaper.

Felix is accused of helping Acosta get the shotgun used in the crime, driving Acosta to the home and attempting to destroy evidence.

After Acosta’s sentencing Friday, some of the victims’ family members made impact statements.