Opening statements got underway Thursday in the trial of a Hauppauge teen accused of killing his stepfather with a samurai sword.Nineteen-year-old Zachary Gibian is accused of slashing and nearly decapitating Scott Nager in February of 2005. Prosecutors say 51-year-old Nager, a retired New York City police officer, was sleeping on the couch when he was attacked by Gibian. Prosecutors began the trial saying that they have a videotaped confession of Gibian admitting to the slaying. The defense claims Gibian was subjected to years of abuse at the hand of his stepfather. Gibian's lawyer also says not a single spot of the victim's blood was found on the teenager's clothes.Gibian is charged with second-degree murder and faces 25 years to life in prison if convicted. Related Information Prosecutors claim new evidence in Hauppauge samurai sword slaying