Pittsburgh Neuroresearcher Accused in Wife's Death Wanted 'Best and the Purest' Cyanide

— -- A University of Pittsburgh medical researcher made an unusual request in ordering the cyanide that prosecutors allege he used to poison his wife, two medical associates testified in the murder trial against Robert Ferrante.

Administrator Patricia Quirin testified that Ferrante had never previously asked her directly to make a purchase for him.

Additionally, Michele Perpetua, a lab manager in the Department of Neurological Surgery, said Ferrante asked her about ordering potassium cyanide, and having it shipped overnight.

“He said he wanted the best and the purest,” Perpetua testified Monday.

The cyanide was purchased in April 2013, two days before Ferrante’s wife, Dr. Autumn Klein, collapsed, prosecutors say. Prosecutors say they believe the couple considered having a second child, and Ferrante, 66, told Klein, 41, to drink the tainted cocktail, saying it helped with fertility.

Prosecutors say Ferrante didn’t want to have additional children, and suspected his wife was having an affair.

Three containers of cyanide were found in Ferrante’s lab, including one that was leaking and required hazmat crews to clean, Pittsburgh Police Detective James McGee testified Monday.

Ferrante has pleaded not guilty to criminal homicide, with his attorney, William Difenderfer, telling the jury there’s no proof his client gave Klein the lethal cocktail. Additionally, medical experts "are not going to even prove that she died of cyanide poisoning,” Difenderfer said.

He suggested the death was either suicide or a mystery.

Jurors last week heard a 911 call placed by Ferrante in which his wife can be heard moaning and breathing loudly.

"Sweetheart, sweetheart, I love you very much," Ferrante is heard saying to Klein while waiting for an ambulance. "Please don't do it, please."

Klein died April 20, 2013, at UPMC Presbyterian, where she was chief of the division of women's neurology and an assistant professor of neurology, obstetrics and gynecology.

The Associated Press contributed to this report.