A 23-year-old Army mechanic convicted of ambushing and executing a couple and their friend while they slept inside a Fullerton home in 2016 was sentenced Friday to life in state prison without the possibility of parole.

An Orange County Superior Court jury last month found Joshua Acosta guilty of the special-circumstances killings of Christopher Yost, 34; his wife, Jennifer Goodwill-Yost, 39; and their friend, Arthur “Bill” Boucher, 28, all of whom were fatally shot inside the Yosts’ home in the early morning hours of Sept. 24, 2016.

Acosta’s first target was Boucher, who was asleep on the couch when he was shot in the head, authorities said. Acosta then moved to the master bedroom to shoot Jennifer Yost between the eyes. When the shotgun jammed, Christopher Yost took the opportunity to try to escape but was shot in the head as he fled, authorities said.

Prosecutors said Frank Sato Felix, 27, of Sun Valley, who also is charged with murder in connection with the slayings, helped Acosta acquire a shotgun and waited in a truck outside the home while the killings took place. Felix, who is being tried separately, has pleaded not guilty.


Fullerton police were alerted to the deaths when they received a call from the couple’s 6-year-old daughter, who reported that her parents had died. Officers found the couple’s 6- and 9-year-old daughters inside the home. They were not harmed, but police discovered the couple’s 17-year-old daughter was missing and possibly at risk. She was found a short time later, police said at the time.

Acosta told police that he carried out the killings to protect the Yost’s then-17-year-old daughter, Katlynn Goodwill, who testified during the trial that Christopher Yost — her stepfather — molested her on a weekly basis when she was between the ages of 7 and 15.

Acosta met the family and Felix in the Southern California “furry” community, a group of people who admire and dress up like animals at various meet-ups and conventions.

Goodwill testified that on the night of the killings, she had planned to tell her mother about the sexual abuse and had asked Felix and Acosta to help her run away. She testified that she let Acosta into the home and then waited in the truck with Felix. She was granted immunity to testify in the case, the Orange County Register reported.


Acosta’s attorney, Adam Vining, tried to paint Goodwill as the villain during the trial, arguing that the teen wanted her mother and stepfather dead. Acosta, who is autistic, is overly trusting and had been manipulated, he said.

hannah.fry@latimes.com

Twitter: @Hannahnfry