(CBS) PITTSBURGH - Sources say the husband of Autumn Marie Klein, a prominent Pittsburgh doctor who died of cyanide poisoning on April 20, bought cyanide two days before her death, CBS Pittsburgh reports.
According to the station, Klein's death is now being investigated as a homicide.
Klein's husband, Dr. Robert Ferrante, who works as a neurology professor at the University of Pittsburgh, reportedly purchased cyanide with a University of Pittsburgh credit card a few days before his wife died from a lethal dose of the poison.
Ferrante's attorney, Bill Difenderfer, told CBS Pittsburgh that his client used cyanide as part of his teaching.
Police say the purchase of the poison so close to his wife's death is part of their investigation, the station reports.
Klein, who served as chief of the division of women's neurology at the University of Pittsburgh Medical Center, collapsed on the floor of her Pittsburgh home and was transported to UPMC Presbyterian Hospital where she later died, according to the station.
Sources say Klein had more than 30 times the lethal level of cyanide in her system, the station reports.
Homicide detectives, technicians from the police crime lab and the FBI - armed with a search warrant - have searched the home Klein shared with her husband and their 6-year-old daughter. Subpoenas were also reportedly issued at the university where Ferrante is employed.
According to the station, police detectives have traveled to Boston and Baltimore in the past week or so to probe the backgrounds of Ferrante and Klein. Police are also reportedly preparing to execute several more warrants in the case.
Sources close to the investigation say Ferrante appears devastated by the loss of his wife and maintains his innocence, the station reports.