SAN FRANCISCO (AP) – A California jury convicted Alan Gimenez of killing his infant daughter Priscilla after medical testimony revealed what some doctors say is a tell-tale sign she had been shaken: brain swelling and bleeding inside her skull and behind her eyes.

More than 20 years later, Gimenez still maintains his innocence, and is now contesting his conviction in court on the grounds that the three symptoms his daughter showed are no longer considered a clear indication of abuse.

“I never shook my daughter. I never abused her,” said Gimenez, who was paroled in June after nearly 24 years in prison.

The case before the 9th U.S. Circuit Court of Appeals is among a spate of recent challenges to “shaken baby syndrome” diagnoses that, like Gimenez’s case, include a similar trio of symptoms without evidence of neck injuries.

Many of the cases also have no additional signs of abuse such as bruising or fractures.

Defense attorneys say new research discredits shaking as the most likely cause of bleeding inside the skull and behind the eyes and brain swelling. But medical experts are divided, with some still putting stock in the three symptoms as a strong indicator of shaking or other abusive head trauma even without other injuries.

The court challenges have had some success.

“There does seem to be a movement in the direction of greater skepticism on the part of the judiciary,” said Deborah Tuerkheimer, a professor at Northwestern’s Pritzker School of Law who has written a book about flawed “shaken baby” convictions.

An Illinois federal judge in 2014 freed a daycare worker who was convicted of killing an infant she was accused of shaking. The judge said recent research “arguably suggests that a claim of shaken baby syndrome is more an article of faith than a proposition of science.”

An Arizona judge in 2012 dismissed a murder charge against Drayton Witt after the county medical examiner said developments in the understanding of shaken baby syndrome and some of the conditions that mimic its symptoms contributed to his decision to reclassify the death of Witt’s girlfriend’s infant son as natural, not a homicide.

Witt had spent 10 years in prison in “blind rage” over being falsely accused of shaking the child to death, he said. While he remains angry, he said he’s moved on.

“I got a new deck of cards,” said Witt, 34, who married his girlfriend and has a 2-year-old daughter with her. “I’m healthy. I’m alive. I’m breathing. I have a roof over my head. My bills are paid. My daughter’s beautiful. My daughter’s healthy. My marriage is great.”

Alma Calderaro is challenging her “shaken baby” conviction in New York on similar grounds as Gimenez. She was accused of shaking a 7-month-old girl while serving as a nanny, leaving the girl brain damaged, and convicted in 2009 of first-degree assault and endangering the welfare of a child.

Abusive head trauma, a condition that includes shaken baby syndrome, is often triggered by frustration from excessive crying, according to the Centers for Disease Control and Prevention. Prosecutors file dozens of new cases alleging shaking each year, although Tuerkheimer said cases involving just the trio of symptoms appear to be rarer these days.

Gimenez’s attorneys say he took his daughter to the hospital on August 10, 1991 after she vomited and showed signs of a seizure. She died a few days later, just 49 days old.

What the San Diego County jury that convicted Gimenez, now 47, didn’t hear was that the girl had been in an out of the hospital and had a blood clotting problem, according to Gimenez’s 2012 petition challenging his conviction. Doctors who have since reviewed her medical records for the defense conclude she likely had bleeding in her skull since birth, and died of a stroke-like blood clot, Gimenez’s attorneys say.

Prosecutors stand by the shaken baby syndrome theory used in Gimenez’s prosecution and cite a rib fracture on Priscilla’s body and a tear under her tongue as additional evidence of abuse. A federal judge in 2013 recommended that Gimenez’s petition be dismissed, rejecting his contention that scientific advances in the understanding of shaken baby syndrome show he is innocent.

Gimenez’s attorneys have appealed the dismissal to the 9th Circuit, which could issue a ruling any day now.

The American Academy of Pediatrics says bleeding inside the skull with brain injury and bleeding behind the eyes are “hallmarks” of abusive head trauma such as shaken baby syndrome, though it cautions that doctors have to consider additional factors, including a child’s medical history and other signs of injury.

“The elements you look for and information you gather hasn’t changed dramatically,” said Robert Sege, a member of the Academy of Pediatrics’ committee on child abuse and neglect.

Patrick Lantz, a professor of pathology at Wake Forest Baptist Medical Center in North Carolina, said the trio of conditions, including retinal hemorrhages, or bleeding behind the eyes, could just as easily manifest itself in cases where the child was accidentally dropped or has an infection or disease.

“People who tell me you can be really sure it’s abuse based on the number, location and type of retinal hemorrhages and the presence of blood and swelling in the skull to me are probably about as scientific as a fortune teller reading tea leaves,” he said.

Copyright 2016 The Associated Press.