A GREEN BAY POLICE OFFICER IS CONVICTED OF MURDER, BUT WHAT IF THERE NEVER WAS A MURDER? -- "48 HOURS MYSTERY" SATURDAY, MARCH 19

John Maloney, a Green Bay, Wis. police officer, was convicted of murdering his estranged wife, Sandy, in 1999, though he has always maintained his innocence. But after Maloney's conviction, the story took an unexpected turn when the prosecutor in his case, Joe Paulus, pled guilty to accepting bribes to fix more than 20 cases. This question now is, did Maloney get a fair trial, and, if not, should he get a new one? Correspondent Susan Spencer reports for 48 HOURS MYSTERY: "A Question of Murder," to be broadcast Saturday, March 19 (10:00-11:00 PM, ET/PT) on the CBS Television Network.

Investigator Sheila Berry, who has taken up Maloney's fight, says there is plenty of exculpatory evidence that wasn't heard at trial. Berry says that includes what the police labeled "apartment suicide notes" written by Sandy. Berry became convinced of Maloney's innocence after consulting a dozen forensic experts.

Prosecutors say Maloney killed his wife because he was desperate to get out of a miserable marriage and begin a life with his new girlfriend. According to the medical examiner, Sandy died by strangulation, and then a fire was set to cover up the crime. But Berry, among others, believes that Sandy could have died from alcohol poisoning -- and that the fire was caused by a lit cigarette -- after she became unconscious. It was well-known that Sandy had serious drug and alcohol abuse problems and, at that time of her death, she was struggling through the final stages of divorce.

Maloney says he was with the couple's three young sons the night Sandy died. All three boys continue to believe in their father's innocence. As Maloney appeals his conviction, the state is investigating whether there was any prosecutorial misconduct in the trial that ended with Maloney being found guilty of murder.

48 HOURS MYSTERY: "A Question of Murder" is produced by Ira Sutow. Susan Mallie is associate producer. Al Briganti is the executive editor and Susan Zirinsky is the executive producer.