A twice-convicted murderer was sentenced Tuesday to a third consecutive term of life in prison for killing his father, with a judge saying the penalty was necessary to condemn the Toronto man's crimes.

The sentence means Dellen Millard must serve 75 years in prison before being eligible to apply for parole.

The 33-year-old was found guilty earlier this year of the first-degree murder of his father, Wayne Millard, a wealthy businessman whose death was initially ruled a suicide.

Dellen Millard was previously convicted in the murders of his former lover Laura Babcock and Hamilton man Tim Bosma, a complete stranger.

Prosecutors had asked for an additional 25 years of parole ineligibility on top of the 50 years Millard must serve in prison without parole for those previous murders.

Justice Maureen Forestell, who presided over the case, said the hope of rehabilitation for Millard was so faint that it played little role in the determination of the sentence.

"Dellen Millard has repeatedly committed the most serious offence known to our law," she said. "It is necessary to impose a further penalty in order to express society's condemnation of each of the murders that he has committed and to acknowledge the harm done to each of the victims. It is not unduly long and harsh."

Forestell found that Millard, who pleaded not guilty, had shot his 71-year-old father through the eye as he slept on Nov. 29, 2012, with the bullet lodging in his brain.

Toronto police began looking into Wayne Millard's death shortly after Hamilton police arrested Dellen Millard and charged him with Bosma's death in May 2013. Police charged the younger Millard with first-degree murder in his father's death in April 2014, but the trial didn't proceed until June this year.

Prosecutors alleged the younger Millard killed his father because he believed millions of dollars in potential inheritance were being squandered on a new aviation business.

Millard didn't take the stand in his defence, but told police his father struggled financially with the new business venture, was an alcoholic and lived with depression.

The defence maintained Wayne Millard killed himself.

The judge said the motive for money played no role in her decision, but she said the circumstantial case turned on a lie Dellen Millard told police after his father's death.

Court heard Millard told investigators that he found his father dead in bed around 6 p.m. on Nov. 29, 2012. He told police he last saw his father alive around noon the day before and had then stayed the night at the home of his friend, Mark Smich.

Phone records presented in court indicated, however, that one of Millard's phones moved from Smich's house around 1 a.m. on Nov. 29 to his father's home where it stayed until shortly after 6 a.m.

"I do not believe the statement of Dellen Millard that he stayed at Mark's," Forestell said when she found Millard guilty. "I find it was fabricated to conceal he was involved in the death of his father."

A coroner found a handgun next to Wayne Millard's body. Forensic officers later found Dellen Millard's DNA on the gun's handle and discovered he had bought the gun from a weapons dealer.