TORONTO — It's a question that has taunted Ontario prosecutors, police and government officials for more than a decade, all the while feeding Canada's queasy, hypnotic fascination with Karla Homolka.

Was it a deal with the devil? Or merely a deal with the devil's disloyal ex-wife?

In exchange for her testimony against ex-husband Paul Bernardo, Homolka pleaded guilty in 1993 to two counts of manslaughter, serving 12 years for her role in the deaths of schoolgirls Kristen French, Leslie Mahaffy and her own 15-year-old sister Tammy.

On the eve of her release, that agreement still gnaws at the Canadian conscience.

Critics say it was a desperate move by Crown officials determined to convict Bernardo without much evidence, a consequence of a bungled investigation that missed key clues -- most notably a pair of videotapes documenting the couple's sadistic crimes.

Those tapes, which portray Homolka as an enthusiastic participant in the rapes rather than the battered wife and victim Crown lawyers depicted in court, have long fuelled the argument that the schoolgirl killer deserved a different fate.

She likely would have earned one, some say, had police found the tapes, which former Bernardo lawyer Ken Murray recovered at his client's behest from a pot light in the couple's lakeside home in Port Dalhousie, Ont., near St. Catharines.

Not so, others insist.

"Videotaped evidence, or its lack, had nothing whatsoever to do with either of the deals that were made with Homolka,'' said Stephen Williams, author of two books on Homolka.

"Getting Bernardo for the murders ...it was more important to get him for the murders than anything else.''

Murray kept the tapes a secret for nearly 17 months, but prosecutors still had them in hand well before Bernardo went to trial in 1995, when Homolka was granted a second deal that gave her immunity for her role in the rape of a woman known only as Jane Doe.

The Crown didn't want to compromise the integrity of their star witness by charging her, but that shouldn't have been a concern, said York University law professor Alan Young.

"Once they had the tapes they should have taken off the kid gloves on Karla (and) maybe rescind her deal,'' Young said.

"She was dispensable as a witness; you didn't have to whitewash her anymore. The jury would still do first-degree murder against Bernardo once they saw the tapes.''

Homolka's testimony was still a critical component of the case against Bernardo, with or without the tapes, said Michael Code, the former assistant deputy attorney-general who directed the plea-bargain negotiations with her lawyer.

"There are certain limits on the videotape evidence,'' said Code, who's now in private practice.

The most obvious is that the tapes do not, in fact, depict the murders of Kristen French or Leslie Mahaffy, Code said. Without that, prosecutors still considered Homolka's testimony essential to convicting Bernardo of first-degree murder.

"The facts speak for themselves,'' Code said. "She was called as a witness and she wouldn't have been called as a witness if (prosecutors) didn't feel she was necessary.''

A judicial inquiry the following year concurred, calling the deal "distasteful'' but necessary for Bernardo's prosecution. But Justice Patrick Galligan's report also concluded that if the tapes had been recovered in 1993, the Crown never would have made a deal with Homolka.

There were other mistakes, too.

A public inquiry into the Bernardo investigation found that co-operation, which might have allowed police to catch up with Bernardo before the French and Mahaffy murders, was sorely lacking between the Toronto and Niagara forces.

"There were times during the separate investigations that the different police forces might as well have been operating in different countries,'' Justice Archie Campbell wrote in his 1996 report.

Case in point was the DNA evidence Bernardo gave to police in November 1990 when he was questioned about a string of rapes in the east-end Toronto suburb of Scarborough -- three years before his capture and one month before the death of 15-year-old sister Tammy, who choked to death on her vomit after she was drugged by her sister and raped by Bernardo.

Bernardo's hair and saliva samples sat on a shelf for 25 months before they were tested. During that time, both Mahaffy and French were killed.

"In hindsight, it is clear that these rapes and murders could have been prevented if Bernardo's sample had been tested within 30 or even 90 days,'' Campbell concluded.

Even the coroner who ruled Tammy's death an accident missed a glaring clue: a large chemical burn mark on the girl's face, a telltale sign of the powerful veterinary drugs Homolka used to subdue her as a Christmas present for her husband.

Tammy's assault was also on the tapes, which together with the French and Mahaffy attacks should have been plenty to convict both Bernardo and Homolka of first-degree murder, said prominent criminal lawyer Clayton Ruby.

Ruby became involved when Bernardo's lawyer Murray quit the case and handed over the tapes to lawyer John Rosen, who would go on to defend Bernardo at his trial. Rosen hired Ruby to ensure the tapes were properly handled.

The failure by police to find the tapes was just one facet of an "inept investigation'' by the Green Ribbon Task Force, headed by Niagara police Insp. Vince Bevan, that found no evidence linking Bernardo to the French and Mahaffy murders, Ruby said. "The tapes could have made a huge difference,'' he said. "It's a strong first-degree murder case against both with the tapes.''

In early 1993, when the only evidence against Bernardo was the DNA linking him to the Scarborough rapes, police made the arrest anyway and a news release was issued linking him to the French and Mahaffy murders.

"There was a premature press release ... indicating that they had caught the serial killer who was loose in St. Catharines,'' said Young.

The ensuing 71-day search of the Bernardo home produced no evidence against Bernardo, even though Homolka had told authorities about the tapes.

"They felt a desperation to conclude the deal (with Homolka), because they realized with each growing day that they had nothing on (Bernardo),'' said Young.

"It was almost as if they were plea bargaining to save face because they already committed themselves to a course of action.''

The search of the home ended April 30, 1993. Homolka's deal was finalized on May 14 and Paul Bernardo was charged with two counts of first-degree murder four days later.

Two weeks prior to the search of the house, Toronto police interviewed Homolka about Bernardo's connection to the Scarborough rapes. At Bevan's request, they inquired about her Mickey Mouse watch, which resembled one French was wearing when she disappeared.

The question tipped Homolka off that she was a murder suspect, said Williams. The next day she was hiring lawyer George Walker; that night, Bevan was offering Walker a deal.

Had the more experienced Toronto police been given a chance to execute their search warrant, said Williams, the damning videotapes likely would have been found and used against both Homolka and Bernardo.

Instead, he said, Bevan used Homolka's confessions as the basis for his search -- a move that effectively shielded Homolka from further charges, regardless of what authorities found.