It may never be known who actually killed Nowra Hill couple Kathryn McKay and Greg Hosa, found incinerated in barrels in the Tomerong State Forest in January 2006.NSW Supreme Court Justice Terrence Buddin said yesterday he could not identify at what time, or by whose hand, the couple were killed because all three offenders told different stories to lessen their involvement in the crimes.Justice Buddin sentenced Kim Leanne Snibson to a 32-year jail term for her role.The 38-year-old will be 60 when she is eligible for release.Her accomplice, Stacey Lea-Caton, 29, is serving 22 years in jail for kidnapping and murdering the couple, while Andrew Wayne Flentjar, 33, is serving a 10-year sentence for assisting in the kidnapping of the couple.Justice Buddin described the crime as being committed with a "considerable degree of callousness" and said Snibson's recruitment of her accomplices displayed a level of calculation and manipulation.Mr Hosa and Ms McKay would have suffered slow and painful deaths at the hands of their captors, Justice Buddin said, after waiting a "not inconsiderable amount of time" in a state of anguish wondering what their fate would be."They were totally defenceless and at the mercy of the offenders," he said.Snibson told the court last month that she was sorry for her role in the couple's deaths. But Justice Buddin said her contrition seemed contrived.Snibson first lured Mr Hosa, then Ms McKay to her Calymea St, Nowra Hill house where she, Flentjar and Lea-Caton tackled and hog-tied and gagged them.Because Flentjar left the crime scene while the couple were still alive, neither Snibson nor Lea-Caton's version of events could be corroborated.Justice Buddin said he could not be sure whether Lea-Caton killed Ms McKay while Snibson was away from the house, and then proceeded to kill Mr Hosa when she returned - as Snibson claimed - or if Snibson killed them both when she returned, as Lea-Caton claimed.Objective evidence showed Ms McKay was suffocated after packing tape was wrapped around her face and Mr Hosa was strangled with electrical tape.Justice Buddin speculated that Snibson and Lea-Caton may not originally have intended to kill them."One possible explanation is one of the victims struggled - and there was evidence Ms McKay did struggle - and in endeavouring to subdue her, the decision was made to kill her and then her husband was killed," he said.The couple's bodies were later forced into 44-gallon drums, which Snibson had taken from the victim's property. That night Snibson and Lea-Caton torched the drums in the Tomerong State Forest.Justice Buddin described Snibson's story as "implausible", "quite fanciful" and tailored to suit inescapable, objective facts.Inside Saturday's Mercury:Had Snibson killed before?What was her motive?