Cedars-Sinai Medical Center

Detectives served a search warrant at Cedars-Sinai earlier this year to obtain disciplinary records for Guillermo Fernando Diaz (Kirk McKoy / Los Angeles Times / May 16, 2013)

A nursing assistant who worked at Cedars-Sinai Medical Center is under investigation for allegedly sexually assaulting two patients while they were heavily medicated and too weak to resist, according to court records and interviews.

The women came forward separately last year and gave Los Angeles police similar accounts about how a male employee assaulted them while they were being treated at the hospital.

Detectives served a search warrant at Cedars-Sinai earlier this year to obtain disciplinary records for Guillermo Fernando Diaz, a nursing assistant who had been assigned to a heart patient area. Diaz, 56, was fired in July, according to the hospital. He declined to speak to The Times.

A district attorney's spokeswoman said prosecutors are reviewing whether to file criminal charges.

In November, the state's Department of Public Health revoked Diaz's nursing assistant certification after conducting an investigation into the sexual assault allegations. In a letter informing Diaz of its decision, the agency said it had substantiated multiple allegations of unprofessional conduct.

One woman who said she was sexually assaulted said she remains traumatized.

"It's devastating," she said, to be victimized "when you're incapacitated and not yourself and weak and scared." The Times generally does not name alleged victims in sex crime cases.

During the LAPD probe, a detective discovered two older sexual assault accusations by patients against Diaz — one dating back 14 years — as well as a decade-old complaint by a co-worker who claimed Diaz raped her after an office party. None of those cases resulted in criminal charges.

Diaz has been interviewed by police several times in the last 14 years and denied sexually assaulting patients or the co-worker, according to the search warrant.

In the wake of the complaints, Cedars-Sinai has taken steps to link previously separate databases of employee records, patient complaints and other information, said hospital spokeswoman Sally Stewart. She said the hospital made the changes to improve tracking of allegations against individual staff members but added that it would be speculation to say whether the new system would have led to earlier action in Diaz's case.

Stewart noted that Diaz was never charged as a result of separate LAPD probes of sexual assault reports made before last year. The hospital, she said, investigated all of the complaints and encouraged the patients who came forward last year to report what occurred to police.

"The totality of all the allegations is completely unacceptable to Cedars-Sinai," Stewart said.

The LAPD investigation was launched last summer after reports by the two patients.

The first said she had been sedated before surgery in April 2013 when a nursing assistant entered her room and offered her a back rub, according to the warrant. The patient said the employee began rubbing her breast and groin area, the warrant stated.

The patient told police she repeatedly told him to stop and tried to yell at him but was too weak from her medication, according to the court document.

"Relax," she said the employee told her, "this will make you feel good."

She identified Diaz in a police photo lineup as the person who touched her, according to the warrant.

Soon afterward, another former patient told the hospital and police that she had been repeatedly sexually assaulted by a male employee in 2009. She said she did not have enough strength at the time to tell the man to stop.

She said a hospital social worker told her that the description of the employee matched Diaz, the warrant stated. The patient did not identify Diaz as her attacker in a photo lineup, according to the warrant.

As the detective searched the LAPD's database of reports and consulted with the district attorney's office, he found other similar allegations previously reported to police. In each case, prosecutors had declined to file charges.