The National Parole Board has some explaining to do.I'm still stunned at last week's courtroom revelation that Manitoba justice officials had no idea their key witness in a disturbing sex assault case was actually a career criminal.Kenneth Allan began his illegal lifestyle way back in 1954 and didn't stop until 1990. In that 36-year period he racked up 88 (!) convictions for pretty much every crime in the book - indecent assault, robbery, escape custody, break-and-enter, drugs, weapons, etc.He was given more than 25 years of prison time (of course he didn't serve anywhere near that) and was also found to have violated his parole on four different occasions.Yet apparently the brains behind the NPB still felt confident enough in Allan that they agreed to wipe his slate clean and grant him a pardon sometime in the late 1990s.So when Allan suddenly found himself straying back to the dark side - and committing his most heinous crime yet - it was as if his entire criminal past didn't exist.Allan, you'll recall, admits to having sex on two occasions in 2001 with a mentally-disabled girl whose birth certificate says she was 21 but in fact was closer to six years old.And that may be generous, given the Crown's submission last week that the woman can barely even write her own name.In any event, Allan - through his lawyer - managed to make an absolute sweetheart of a plea bargain with Manitoba Justice last year.He agreed to admit guilt and testify against the co-accused - who happens to be the victim's former respite worker he claims set the sexual encounters up - in exchange for no jail sentence.The Crown was banking on the fact he was an otherwise law-abiding citizen whose credibility would stand up under rigorous cross examination.Instead, they watched their "star" witness come plummeting down to Earth after his dark secrets were uncovered.We will learn this Friday if Allan's testimony was worth anything at all when the judge rules on whether the respite worker is guilty.In the meantime, I think we all deserve an explanation on how someone with Allan's track record was able to get a pardon in the first place.Even people who make a living representing criminals on these kinds of applications are having a hard time believing it. Lucy Perillo, who works out of Winnipeg for Pardon Services, joined me on my national radio show Sunday night and said she's never seen someone with so many convictions as Allan get a pardon.Usually, she says, the applicants have one or two indiscretions they're hoping to clean up.But 88???None of this would have even been discovered if not for convictions number 89 and 90 - the two sex assaults Allan admitted to last year.That meant the parole board revoked his pardon and everything came back into play.Unfortunately, the justice system has no way of going back in time and revoking Allan's conditional sentence and giving this creep exactly what he deserves - a long stint behind bars.Keep the discussion going - and make your voice heard - by posting your thoughts below.