COLUMBUS, Ohio — An Ohio ex-doctor was responsible for the death of an expectant mother who died after answering a Craigslist ad for housecleaning services, according to a $40 million lawsuit that also targets the physician's employer and Craigslist.

The lawsuit filed Monday in county court north of Columbus blames former physician Ali Salim for the death of Deanna Ballman last summer.

Craigslist should have known Salim was dangerous because other women who responded to ads Salim placed had experienced problems that were reported to police and Craigslist, according to the lawsuit.

"Craigslist was on notice and knew or should have known defendant Ali Salim was inherently dangerous to its Internet users," said the lawsuit, filed on behalf of the woman's family.

It also says Salim's employer, Knox Community Hospital, was negligent for allowing him to take syringes that the lawsuit says were used to inject Ballman with heroin. Messages seeking comment were left Tuesday for the hospital and Craigslist.

The lawsuit also alleges someone helped Salim inject the 23-year-old woman with heroin, something investigators say they've tried unsuccessfully to prove.

Nine months pregnant, Ballman was alive on July 31, 2012, when Salim placed her in the back of her car and drove her to a rural road in Delaware County where she was found dead the next day, according to the lawsuit.

Investigators, including the Delaware County coroner, have previously declined to say when Ballman died.

Salim has pleaded not guilty to kidnapping, raping and killing Ballman by injecting her with heroin, as well as killing her unborn daughter, to be named Mabel Lilly. His criminal trial, originally scheduled for September, has been moved to Oct. 29.

Salim's attorney, Sam Shamansky, has said Ballman was prostituting herself to feed a drug habit. A message was left with Shamansky on Tuesday.

Authorities say there's no evidence she was a drug user, but they have said Ballman was responding to a personal ad, not a housecleaning ad.

Women who previously answered ads placed by Salim reported being accosted, sexually assaulted or asked to be alone in the house while he painted the human digestive system on their abdomens.

The lawsuit was filed before the anniversary of Ballman's death "to preserve certain claims," attorney Gregory Helser, representing Ballman's sister, Cynthia Skoda, said Tuesday without elaborating.

Ballman had recently returned to central Ohio from Colorado where she had served in the National Guard. She had two small children and was working odd jobs to make ends meet until her third child was born, according to her family and the lawsuit.

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Andrew Welsh-Huggins can be reached on Twitter at https://twitter.com/awhcolumbus.