Investigators now believe a drug overdose may have caused the death of a Long Island dermatologist who was found unconscious in a Manhattan apartment vestibule on Sunday morning. A source tells the Daily News that Kiersten Cerveny's death seems "consistent with cocaine use."

"Based on the preliminary finds, we are not treating this as a homicide case," the source elaborated. "There is nothing at this point to suggest criminal activity. We have no indication, so far, of any force issue in her death.”

Cerveny, a 38-year-old mother of three who had practiced dermatology in Manhattan and Brooklyn and lived in Manhasset, had gone out with girlfriends on Saturday night. The NY Post's sources say she went bar hopping downtown starting around 6:30 p.m., and later met up with HBO producer Marc Johnson on the Lower East Side. Johnson, 51, is married and lives in Tribeca.

It appears that Cerveny and Johnson later went to visit James "Pepsi" Holder who lives at 223 West 16th Street in Chelsea around 4:25 a.m. From the News:

Four hours later, Holder and Johnson were seen dragging the woman to the front door of the W. 16th St. building, the sources said. Johnson tried to perform CPR on the lifeless woman and called 911 after “she turned blue,” he told detectives.

Johnson stuck around until EMS arrived, directing them to the lobby where Cerveny was wedged between two sets of doors, sources said. Both men were gone by the time cops arrived, a police source said.

Cerveny was pronounced dead at 9:12 a.m.

Johnson, 51, who is married, was "tracked down" by detectives and questioned; sources tell the Post he "admitted using coke with Cerveny before clamming up and asking to speak with a lawyer." He has not been charged.

Sources tell the News that Holder, 60, is a suspected drug dealer who goes by the nickname Pepsi "because 'Coke' was too obvious."

Cerveny had three children, ages one to seven, with Andrew Cerveny, also a dermatologist; their NY Times wedding announcement said they "met in 2004 as residents at the Medical Center of Louisiana at New Orleans." She worked at hospitals and practices in Brooklyn and Manhattan.

A former winner of the America's Junior Miss pageant, Cerveny also taught water ballet at the Strathmore Vanderbilt Country Club. A club member told the Post that she was a "great mom... Everybody thinks it’s horrible that this is what she’s going to be known for."

Newsday reports that no one answered the door at the Cervenys' home. A neighbor said, "It's devastating. It's really sad. She seemed very sweet."