July 30, 2013  -- A University of Pittsburgh researcher who allegedly laced his wife's creatine drink with a lethal dose of cyanide pleaded not guilty today to criminal homicide.

Dressed in an orange jail uniform and with his hands shackled, Dr. Robert Ferrante, 64, appeared in a Pittsburgh court today, one day after he waived extradition from West Virginia, where he was arrested last Thursday.

Ferrante's attorney, William Difenderfer, said his client was traveling from Florida to turn himself in to police in Pittsburgh when he was pulled over in West Virginia.

"He's anxious to defend himself, have his day in court and prove his innocence, which I'm quite confident we'll be able to do," Difenderfer told ABC News.

Investigators believe Ferrante, who is considered a leading researcher of Lou Gehrig's disease, killed his wife, Dr. Autumn Klein, 41, by lacing her creatine energy drink with cyanide April 17, the same day the couple exchanged text messages about how a creatine regimen could help them conceive their second child, according to a criminal complaint.

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

"According to my calendar I ovulate tomorrow," Klein wrote in a text message April 17.

Police say Ferrante responded, "Perfect timing. Creatine."

"Will it stimulate egg production too?" Klein asked in another message.

Ferrante allegedly responded with a smiley face.

Authorities previously acknowledged Klein had cyanide in her blood when she died but did not publicly label her death a homicide until Thursday.

When paramedics responded to Klein's medical emergency April 17, they saw a glass vial near a resealable, plastic bag holding a white substance, which Ferrante told them was creatine, the criminal complaint said.

On April 15, two days before Klein collapsed, Ferrante used a university credit card to buy more than a half-pound of cyanide, according to the complaint, despite having no active projects that involved the chemical.

Later, in the days before Klein fell ill, a witness saw Ferrante drinking samples of creatine mixed with water and sugar in the lab, according to the complaint.

Police say the witness told them Ferrante put the creatine in a large, resealable bag and that the cyanide was locked in a safe that was only accessible to Ferrante and one other person.

A witness at the hospital told police, according to the affidavit, that Ferrante said, "I'm going to spend the last night with the love of my life" while Klein was still alive and being treated.

Police documents also allege "Ferrante did not want an autopsy performed" and instructed that Klein's body be cremated. Despite those instructions, police said, an autopsy was performed and revealed the cause of death as "cyanide poisoning."

Police have not released a possible motive but said they've found evidence Ferrante believed Klein was having an affair and confronted her about three times in the weeks leading to her death.

In February, while attending a conference in San Francisco, Klein told a male friend that she planned to leave her husband, according to the complaint.

During the time Klein confided this to her male friend, according to the criminal complaint, she received a text message from Ferrante, who said he was coming to the conference.

Klein told her friend this was Ferrante's "controlling nature," according to the complaint, and that he believed there was "something going on" between her and the male friend.