PITTSBURGH (AP) — A university medical researcher who allegedly poisoned his neurologist wife by lacing an energy drink with cyanide pleaded not guilty Tuesday to criminal homicide.

Dr. Robert Ferrante, 64, was arraigned in Pittsburgh a day after waiving extradition from West Virginia, where he was arrested last week.

Defense attorney William Difenderfer has said Ferrante "adamantly" denies involvement in the April 20 death of his wife, Dr. Autumn Klein, 41, three days after she suddenly fell ill. But after the arraignment, Difenderfer refused comment on any of the allegations, including that Ferrante bought the poison with a university credit card two days before his wife fell ill.

Doctors at University of Pittsburgh Medical Center-Presbyterian hospital, where Klein and Ferrante worked, were puzzled by her sudden illness and considered everything from a stroke to a seizure disorder in treating her. Blood tests revealed a lethal level of cyanide, but only after Klein had died and been cremated at her husband's insistence, police said.

During the hearing, Difenderfer said Ferrante, who appeared on video from the county jail wearing a white dress shirt beneath his red jail jumpsuit, remains "devastated" by his wife's death.

Difenderfer said the celebrated researcher of amyotrophic lateral sclerosis, or Lou Gehrig's disease, has never been in criminal trouble before.

A preliminary hearing scheduled for Aug. 9 was immediately rescheduled for Sept. 23, and Ferrante remained jailed without bond.

City police charged Ferrante after discovering he bought more than a half-pound (2.25 kilograms) of cyanide, which police determined was not related to his research.

The criminal complaint indicated Klein may have been trying to get pregnant by Ferrante — with whom she already had a 6-year-old daughter — and that he suggested drinking creatine might improve their chances of conceiving, even though the supplement is not known to aid reproduction. The complaint also suggested, however, that Ferrante suspected Klein was having an affair.

An affidavit and several search warrants suggest Ferrante plotted to poison his wife, then took steps to delay her medical care and keep the cyanide from being detected.

Among other things, police said Ferrante told an emergency dispatcher he wanted his wife taken to another hospital a mile (two kilometers) farther from their house than UPMC Presbyterian, which has a top-rated trauma center. And witnesses at the hospital told police Ferrante's reactions "seemed fake and like 'bad acting'" and that he spoke of her in the past tense when she was still alive.