Man gets life in prison without parole for Fullerton murders of trio with ties to ‘furry’ community

A Sun Valley man described as the mastermind of the triple killings of a Fullerton man and woman he met in the “furry community” along with a friend of the couple was sentenced Friday, April 11 to life in prison without the possibility of parole.

Frank Sato Felix, 33, was convicted in November 2024 for the special circumstances murders of Jennifer Yost, Christopher Yost, and Arthur “Billy” Boucher.

All three victims were gunned down with a shotgun while sleeping in the early-morning hours of Sept. 24, 2016, at the Yosts’ Fullerton home.

Prosecutors at trial said before the slayings, Felix had become “obsessed” with the couple’s teenage daughter, who they told Felix to stay away from.

Felix, who was shackled and wore a jail-issued blue smock, green pants, and orange shoes, described himself as a “beast” at the Friday hearing as he choked back tears while reading from a brief apologetic statement prior to being sentenced by Orange County Superior Court Judge Kimberly Menninger.

“To the families and the victims, I would trade places in a minute with those who were killed,” he said.

Amy Rutherford, Christopher Yost’s sister, asked in a victim impact statement that Felix receive the maximum sentence. “No sentence can erase the horrors of that night (when the slayings occurred),” she said, adding her continual grief has left her feeling fragile and hollow.

The murders also have taken a toll on the Yosts’ two younger children, who discovered their parents dead, said Rutherford. “Every milestone they reach will be tinged with loss,” she added.

David Paulson, Felix’s attorney, described the murders as “brutal” and “senseless.”

He told the judge, “There are no words that can be offered to ease the pain of the victims’ families. He (Felix) will grow old behind bars and will never walk free again. His expressions of remorse go beyond what he has communicated to me.”

Felix’s parents attended the hearing but did not address the court. “They are not here to defend what can’t be defended,” Paulson said. “They are here because he is their child.”

Felix, who was 25 at the time of the slayings, has admitted providing the actual gunman – then-21-year-old Joshua Acosta – with a shotgun and ammunition and waiting outside the Fullerton home with the Yost’s then-17-year-old daughter while Acosta killed the couple and Boucher, who was spending the night at the residence.

Boucher was killed while he slept on a couch, Jennifer Yost while she slept in her bed and Christopher Yost after he awoke and attempted to escape the home.

Felix, the Yosts and their teenage daughter were all part of the furry community, comprised of people who role play and sometimes dress up as animal characters and take on their personas as they congregate online and at conventions. Acosta – at the time an Army mechanic – was a “Brony,” a man who is a fan of the “My Little Pony” series.

Senior Deputy District Attorney Seton Hunt has said Felix orchestrated the killings and was obsessed with the then 17-year-old daughter whom the Yosts had ordered him to stay away from. At one point shortly before the killings, Felix wrote to the teenager, “You are the only one and thing that makes me happy.”

The daughter – who testified during Acosta’s trial but did not take the stand in Felix’s trial – claimed that her stepfather, Christopher Yost, sexually abused her and her mother, Jennifer Yost, verbally and physically abused her. Following their arrests, Felix and Acosta told police that they were trying to “save” the daughter from her parents.

Menninger said had it not been for the daughter’s untruthfulness about being abused by her parents, the slayings wouldn’t have happened.

“He (Felix) thought he was doing something courageous, all of which was a lie,” she said.

It’s unknown whether the abuse allegations are true, authorities have said. It also remains unclear whether the girl knew of the plot to kill her parents.

She has alleged Felix blackmailed her into having sex with him and admitted letting Acosta into the home just before the killings began.

Felix only intended to help the 17-year-old “escape” her mother and stepfather, Paulson, his attorney, has said. It was Acosta who wanted the gun and ammunition for protection in case Jennifer Yost or Christopher Yost tried to stop him, he added.

Days before the killings, Felix wrote in a Facebook message to a friend, “I might be assisting someone with murder,” then claimed he was just talking about an animal when the friend told him not to do it

The Yosts’ two younger children were asleep and not harmed during the shootings, but awoke to find their parents dead. Officers quickly realized the older daughter was missing and through her phone records identified Acosta as a suspect.

Authorities at Fort Irwin, where Acosta was stationed, detained and searched Acosta and found three shotgun shells in one of his pockets. One shell, a prosecutor noted during his trial, for each victim.

In a police interview shortly after his arrest, Felix admitted buying ammunition, ear protection and a bolt cutter to cut a security lock off his father’s shotgun, which he gave to Acosta.

Felix described being afraid of Acosta, and claimed he only heard the final gunshot. He acknowledged that the daughter had told him earlier that night that Boucher was staying at the home, explaining to police, “So I already knew there was going to be a third body.”

Acosta told police the Yost family was a “festering wound” that he had “cauterized,” and described Boucher as “collateral damage. He was sentenced  in 2018 to life in prison without the possibility of parole.