A doctor’s manner of death was labeled “undetermined” after a lethal mix of drugs was found in her system when she died alone in her firefighter boyfriend’s home, three years after her previous fiancé was found shot to death. .

A doctor died from a lethal mixture of drugs, but the manner of her death has been labeled “undetermined” as the mystery surrounding her death grows.

Dr. Sarah Sweeney, 39, was found dead at the home of her fiancé, local fire captain Robert Daus, in suburban St. Louis on January 13.

On Tuesday, a toxicology report from the St. Louis County Medical Examiner’s Office revealed that the doctor’s cause of death was drug intoxication, but the manner remains undetermined. Oxycodone, the seizure and pain medication gabapentin, and the antihistamine diphenhydramine were found in Sweeney’s system.

‘Dr. “Sweeney was found with no obvious signs of trauma discovered on her body, and our investigation, at this point, supports that she was home alone prior to her death,” the Frontenac Police Department stated.

She is the second woman engaged to Daus to die in recent years. Grace Holland was found dead in 2020 from a gunshot wound. Her death was initially ruled a suicide, but the investigation into Holland remains “active,” authorities said.

Following Sweeney’s death, police reopened the investigation into Holland’s death in July 2020 and their investigation “remains active.”

Daus, a captain with the Maryland Heights Fire Department, has not yet been named a suspect in either case and has denied any involvement in their deaths.

Born in West Virginia, Sweeney moved to Missouri to open her own podiatry practice in Creve Coeur.

Her mother, Teresa Sweeney Light, said, “I wish we could get her back.” “We just want closure, we want it to be truthful and fair, and until now, we are still in shock.”

According to her mother, Daus and Sweeney met when she was working a shift in the emergency room shortly after moving to St. Louis.

‘Sarah was a vibrant, outgoing person who never met a stranger. “She loved dogs and cats, and over the years she rescued and owned several of them,” her obituary read.

“Sarah was diagnosed with Perthes disease when she was six years old, which caused her a lot of physical pain throughout her life.”

Federal court documents reviewed by DailyMail.com revealed that Sweeney lived in fear of Daus and described him as “suspected of murdering a previous girlfriend.”

Sweeney’s claims emerged in court documents that are part of a lawsuit he filed against his former employer Best Foot Forward and its founder, Dr. Franklin Harry, in November 2022.

Sweeny emailed a friend: ‘But guess what, Danielle? I have been homeless, had to move in with my ‘killer’ boyfriend which has been scary at times, lost every penny and closed my savings account, had trouble getting a job because of my past. affiliation with him, I have suffered… I have been through the test.’

Holland’s family has filed a wrongful death lawsuit alleging that Daus is responsible for Holland’s death and that he was psychologically and physically abusive.

Daus has never been charged in connection with Holland’s death, which the medical examiner ruled was a suicide despite several key factors that her family says contradict this finding.

They point out that Holland was right-handed and as a woman trained in the use of firearms had always shot with her dominant hand.

However, she was shot in the left temple, an event described by her family as “inconsistent” with a self-inflicted wound and “consistent” with someone standing in front of her shooting her.