PITTSBURGH — A University of Pittsburgh 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.