SAN JOSE — New evidence retrieved from a broken cell phone has led to a stunning development in the case of Phoenix Castro, the three-month-old who died of a fentanyl overdose in May 2023: her father and the dealer police say sold him the killer drug the night before have been charged with murder.

The case is Santa Clara County’s second-ever murder prosecution over a child’s deadly fentanyl overdose, and a reputed San Jose drug dealer is charged in both — for Baby Phoenix’s death and for 19-month-old Winter Rayo’s death three months later, when her parents left fentanyl within reach. The two men were arraigned in Friday on the new charges.

Baby Phoenix’s death two years ago had already upended the county’s child welfare system, leading to major reforms and a new director, after investigations by Bay Area News Group found agency leaders ignored a social worker’s dire warnings that the newborn would be in perilous danger if sent home with her drug-abusing father.

David Anthony Castro, 40, had been in jail on a lesser felony child endangerment charge and becomes the county’s third parent to face a murder charge over the fentanyl death of a child. The other two are Baby Winter’s parents, Derek Rayo and Kelly Gene Richardson of San Jose.

The cases share a central figure: 33-year-old Phillip Michael Ortega. Authorities say he first sold fentanyl to Castro that wound up on Baby Phoenix’s pink-flowered onesie, then continued to supply the same drugs to Baby Winter’s parents — Ortega’s housemates — until the toddler consumed enough to kill an adult.

“The deadly nexus between the fates of these two babies is Phillip Ortega,” District Attorney Jeff Rosen said Friday. “Baby Phoenix and Baby Winter are gone, and defendants Ortega and Castro, the father, will be held fully and fairly accountable in a court of law.”

The murder charges for Castro and Ortega allege malice aforethought, indicating prosecutors intend to argue the two acted with extreme and reckless disregard for human life. That exposes them to a second-degree murder conviction that carries a minimum prison term of 15 years to life.

Ortega’s attorney, Renee Hessling, said her client was being irresponsibly portrayed and that prosecutors face stark challenges in proving murder.

“The District Attorney’s Office wants nothing more than to try this case in the court of public opinion and exploit the tragedy of a young baby’s death for their own political gain,” Hessling told this news organization. “This prosecution ignores the enormous legal hurdles of establishing murder liability for a man that had nothing to do with the baby, let alone a legal or moral relationship with the baby.

“The defense intends to fight vigorously against these inflated charges — Mr. Ortega is not a murderer, plain and simple.”

At Friday’s arraignment, Hessling and Deputy Alternate Defender Mishya Singh, who is representing Castro, entered not guilty pleas for their clients and a preliminary examination was scheduled for July 28. But given the typical timeline to litigate a murder case, that hearing will likely be continued to a later date.

Singh’s office, backed by Hessling, sought a temporary gag order for the case, arguing the DA’s office was damaging the defendants’ rights to a fair trial with its public comments, and complained that they first learned about the murder charges from news coverage. Prosecutors argued their media comments were in line with an elected office keeping the public apprised of their work; Ramon denied the gag order request.

Fentanyl has claimed the lives of at least five Bay Area infants or toddlers since 2020. Parents in four of the cases — in Brentwood, Livermore and San Jose — have been charged with murder. A mother in Fremont pled guilty to a charge involuntary manslaughter charge last year for the fentanyl death of her 23-month-old son.

An investigator’s affidavit filed Thursday states that Ortega’s broken cell phone was finally repaired enough for authorities to recover key text messages and location data showing he went to Castro’s South San Jose apartment with fentanyl for sale on May 12, 2023, bolstering their stance that Castro lied to police about using drugs the night before his baby died.

Both men “knew the dangers of overdose and death due to drugs and fentanyl, especially the dangers to a baby,” according to an affidavit filed by District Attorney Investigator Sheena Woodland, in her explanation for recommending murder charges.

Investigators earlier alleged Castro also lied about when he discovered his daughter’s death. Instead of calling 911 right away, the affidavit asserts, he called someone to obtain synthetic urine from a smoke shop that didn’t open until 10 a.m. He wanted to pass a drug test, which he ultimately did.

Authorities further contend that only after Castro secured the fake urine did he call 911 and tell the dispatcher he fell asleep on the couch the night before with the baby swaddled in his arms and awoke mid-morning to find her face down on the couch, not breathing.

Castro was held over for trial on the child endangerment charge after a preliminary examination. He has since sought to avoid trial and potential prison time by asking a court to divert him to a mental health program, claiming his troubled childhood and health problems made him turn to drugs.

Singh referenced that request in her response to the new murder allegation.

“The prosecution filed this baseless charge, 21 months after initially deciding that murder was not an appropriate allegation, a move clearly meant to keep Mr. Castro from receiving a hearing on a motion at which he could have received the court supervised treatment he needs,” Singh said in a statement to this news organization. “Such gamesmanship is no way to operate a justice system that should be productively seeking justice for Mr. Castro and Phoenix.”

Prosecutors vehemently fought court diversion for Castro, arguing that if he needed help, he could have sought out prescription drugs. He had already lost custody of his two older children because of severe neglect and their mother, who was in a drug treatment program when Baby Phoenix died, died of a fentanyl overdose months later.

“My hope, my prayer, is that these two dead baby girls will change things for the better,” Rosen said. “I hope we honor their memory by preventing future horrendous crimes.”