The 38-year-old Long Island doctor found dead in the vestibule of a Manhattan apartment building had been using cocaine inside an apartment there with a boyfriend and another man before they left her in a lobby to be picked up by EMS, multiple law enforcement sources say.

An autopsy was conducted Monday on Dr. Kiersten Cerveny, a dermatologist who lived in Manhasset and was a married mother of three, according to sources and a post on her Facebook page. The medical examiner's office said late in the afternoon that they were awaiting toxicology and other tests for more clues about her death.

Law enforcement sources told NBC 4 New York Monday that Cerveny became ill after consuming cocaine inside an apartment of a five-story walk-up building on West 16th Street. The two men she was with tried to carry her to a cab downstairs, but she collapsed, the sources said.

The men called 911, and when EMS arrived, the man believed to be her boyfriend fled back upstairs, the sources said.

Emergency medical technicians attempted to resuscitate Cerveny as they loaded her into the ambulance and took her to the Lenox Health emergency room in Greenwich Village. She died at the hospital.

Investigators initially said they were looking for an unidentified man who was thought to have spotted the unconscious Cerveny in the vestibule and flagged down an ambulance before fleeing. Police said Monday the man now believed to be Cerveny's boyfriend was questioned, but neither he nor the other man is expected to face charges.

Cerveny's father told the Daily News that she had told her husband she was headed out from their home in Manhasset to spend the night in the city with a friend.

Cerveny had been drinking at a Lower East Side nightspot before arriving by cab with a man at the apartment building around 4:30 a.m. Sunday, police said. Investigators recovered security video that showed the man and another person carrying her into the entryway about four hours later.

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Cerveny, who was originally from Washington Township in Gloucester County, New Jersey, had been an assistant professor of clinical dermatology at Weill Cornell Medical College, according to a Dec. 12, 2009, announcement of her marriage to Andrew Cerveny Jr., also a dermatologist, in The New York Times. She graduated magna cum laude from Duke University and earned her medical degree at Tulane University.

She met her husband in 2004 while both were residents at the Medical Center of Louisiana at New Orleans. No one would comment at his Long Beach office Monday.

"It's just mind-boggling,'' said Thomas Nicotri, one of Cerveny's professors during her residency in New Orleans and who had seen her and her husband at dinner two months ago. "They looked healthy and happy. It seemed like they were on top of the world. They had everything.''

"She was intelligent, caring and very professional,'' Nicotri said. "I never had any concerns about her at all.''

Scott Wyosota, a neighbor of the Cervenys in Manhassett, said she was "a very vibrant, very alive, dedicated mom."

Cerveny's achievements included winning the 1995 America's Junior Miss competition as a teenager from Blackwood, New Jersey. The prize was a $30,000 scholarship she used to attend Duke.

An outpouring of grief from friends and acquaintances was evident on Cerveny's Facebook page Monday morning.

"So saddened to hear of this news. Our hearts and prayers go out to your family Kiersten Rickenback Cerveny especially your three beautiful children," wrote one poster. "Rest in peace."

Another woman wrote of knowing Cerveny since they were young girls taking gymnastics together; she called her a beautiful and intelligent woman who had a gorgeous family.

Still another referred to Cerveny as "the light of our pledge class."

Several women expressed shock and anger on Cerveny's Facebook page over what they described as a "tragic loss." One said, "My heart is breaking."

"I think back to those first days at Randolph. You were so stunning it was intimidating," another woman wrote. "But, as we all quickly learned, your inner beauty trumped any physical beauty."

Cerveny's work as a doctor also drew praise on the social media app Yelp. Posts there called her "a beautiful soul," "friendly, helpful, awesome" and a "doctor with a great bedside manner, very kind and encouraging."