A 71-year-old Thornhill gynecologist should be found guilty of manslaughter because he failed to call 911 after injecting his wife with a deadly mix of drugs, a Crown attorney said on Tuesday.

"Dr. (Joseph) Roncaioli recklessly or deliberately injected (his wife) with a cocktail of drugs that caused her death," prosecutor Martin Dionne said inside a Newmarket courtroom.

"In her hour of need, he failed to help her in any way. That, ladies and gentlemen, is manslaughter."

Roncaioli has pleaded not guilty to manslaughter in the July 20, 2003 death of his wife of more than 30 years, Ibi Roncaioli, 67.

She was in the news in 1991 after winning $5 million in a lottery jackpot.

In his opening address, Dionne said Roncaioli had been acting strangely and drinking on the day he injected his wife.

After the doctor committed the act, he failed to call police or attempt to revive his wife, but instead called his bookkeeper and a real estate agent, Dionne said.

Jurors were told the couple had met with the real estate agent earlier that day to discuss their recent purchase of a new home, valued at about half their million-dollar Thornhill mansion.

It was the bookkeeper who eventually called an ambulance, said Dionne, who added Roncaioli waited nearly six months before telling anyone he had injected his wife.

Ibi's cause of death was ruled as multiple drug toxicity.

Despite their fortunate lottery win, the couple's net worth was a little more than $300,000 at the time of Ibi's death.

With a report from CTV Toronto's Chris Eby