The mother of the accused Hauppauge man in the samurai sword slaying trial is refusing to testify.Laura Nager, Zachary Gibian's mother, was subpoenaed but will not have to take the stand since she has pleaded the fifth. Gibian has testified that he only confessed to killing his stepfather, Scott Nager, to protect his mother. He claims his mother is the real killer. Prosecutors have called Gibian a liar. Gibian's attorney said he was hoping the jury would have heard from Laura Nager, but she has a legal right not to take the stand. The move has also upset Scott Nager's father, Nathan Nager. He said he also was hoping to hear from his daughter-in-law and that she might have revealed something no one knew. Nathan Nager said he firmly believes his grandson is guilty of the crime.Closing arguments in the case could come as early as Monday afternoon or Tuesday.Related Information: Police release graphic confession of Hauppauge sword murder suspectHauppauge teen admitted to samurai sword murder, ex-Met's son claims Defense claims suspect's mom could be Hauppauge sword murderer Retired cop from Hauppauge killed by samurai sword, stepson arrested Defense claims Hauppauge teen charged with killing stepfather was abused Judge rules mother can use bail money in samurai sword murder case Prosecutors claim new evidence in Hauppauge samurai sword slaying Trial begins for Hauppauge teen accused of killing stepfather with samurai sword Prosecutors scour ex-Met's phone records in Hauppauge samurai sword murder Hauppauge teen points to bloodless clothes in samurai sword trial