Updated

The commander of Canada's largest air force base stalked, repeatedly raped and killed two women as they pleaded for their lives, prosecutors said Tuesday at the colonel's sentencing hearing.

Col. Russell Williams, who once flew prime ministers and served as a pilot to Queen Elizabeth II during a 2005 visit, pleaded guilty Monday to two first-degree murder charges, two sexual assaults and 82 breaking-and-entering charges during which he stole lingerie belonging to teen girls and young women.

The 47-year-old faces an automatic sentence of life in prison with no possibility of parole for at least 25 years. Lawyers have used the sentencing hearing to reveal details of the crimes.

Prosecutors warned the court that details of the killings were horrific before explaining how Williams bound, beat, raped, photographed, videotaped and asphyxiated Marie Comeau, a 37-year-old corporal, and Jessica Lloyd, 27.

Comeau made one final plea for her life before Williams suffocated her, said prosecutor David Thompson.

"Have a heart, please," Thompson said Comeau begged. "I've been really good. I want to live."

Thompson told the court that Williams met Comeau while she was working as a flight attendant on a military flight and discovered she lived alone.

As a colonel, Williams had access to her work schedule and broke into her home Nov. 16 while she was away to confirm she lived alone. He repeated the same pattern the court learned he undertook during dozens of other break-ins, stealing her lingerie and photographing the bedroom and images of himself modeling the undergarments with his erect genitalia protruding.

A week later, prosecutors said he returned when he knew Comeau would be home, carrying a kit filled with duct tape and zip ties. Williams was masked for most of the attack and there was no indication from prosecutors that she knew who he was.

Thompson said Williams entered the home, hid in the basement and waited for Comeau to fall asleep before attacking her. His plan was foiled when Comeau headed to the basement in search of her cat. Williams, in an attempt to subdue an alarmed Comeau, struck her numerous times with a flashlight to the point where she was bleeding from the head.

Williams tied her up to a basement post and covered her mouth and eyes with duct tape, Thompson said. Williams later took her upstairs where he repeatedly sexually assaulted her for more than two hours, taking video images and still photographs.

Thompson said Williams ordered the woman into positions for better video footage and at one point removed his mask to smile for the camera. As he forced himself on her, Comeau's lips quivered as she pleaded for him to stop. Thompson said Williams placed duct tape on her nose to suffocate her and continued taking photos as she struggled for breath and died.

After he placed her dead body on her bed, Williams left with Comeau's lingerie and drove to Ottawa for a meeting about the purchase of a C-17 aircraft.

Two months later, Williams noticed Jessica Lloyd while driving by her home on a rural stretch of highway where he had a cottage.

Williams went to Lloyd's home on Jan. 28, and waited in her backyard for her to go to sleep before entering her bedroom. Once inside, he bound her with rope and placed duct tape on her face. He took photos of the repeated rapes and sexual assaults.

Prosecutor Lee Burgess, who held back tears as he recounted details of the gruesome crime, said after three hours of rape and abuse, Williams drove the blindfolded Lloyd to his home in Tweed. Burgess said that Williams told police he let her sleep for a few hours and she began to seizure. She pleaded for her life and asked to be taken to the hospital.

"I don't want to die. If I die, will you make sure my mom knows that I love her?" Lloyd said on a videotape that Williams kept rolling despite her convulsions and intense struggling, according to prosecutors. Sobs rang throughout the courtroom as the prosecution described this sequence of the videotape.

A day and a half after the ordeal began, Williams strangled Lloyd with a rope.

Prosecutors said Williams then drove back to his base in Trenton to catch an early military flight the next morning to California. When he returned from the West Coast the next day, he drove to his Ottawa home and then to Tweed the following day to remove her body from his cottage.

Williams sat slumped with his head down in court as prosecutors detailed the evidence.

Until his double life came to light with his arrest earlier this year, Williams was moving up in the Canadian Air Force ranks.

The charges against the elite pilot — a tall, fit figure who did his job with quiet diligence and appeared to be in a stable marriage — shocked the country and its military with the possibility of a serial killer in its officer corps. A 23-year military veteran, Williams had never been in combat but had been stationed across Canada and internationally, including a stint in 2006 as commanding officer of Camp Mirage, the secretive Canadian Forces base widely reported to be near Dubai.

Williams was photographed in January with Canada's defense chief and its top general during an inspection of a Canadian aircraft on its way to support relief efforts in earthquake-stricken Haiti. Williams killed his second victim just over a week later.

Besides details of the murder charges, the court learned earlier this week Williams targeted girls and women in their 20s during his underwear fetish break-ins, stealing their lingerie and photographing himself modeling the underwear while he masturbated in their homes while they were away. Burgess said Williams carefully catalogued the photos with time and date stamps on hard drives in his Ottawa home, as well as the hundreds of items of lingerie he stole.

The prosecution said Williams confessed to all of the charges, saying he killed both women because he feared investigators would determine a link between all of the sordid crimes and to minimize the impact on his wife. He also lead investigators to Lloyd's body. The court will watch his three-hour videotaped confession on Wednesday.