Lisman was found dead in her Ephratah home on Mud Road in July 2013. Fulton County District Attorney Louise Sira said Lisman suffered from two shots to the back of the head.
Sheriff Thomas Lorey said at the time of Dibble's arrest investigators believe Dibble and his mother had been arguing over money in recent days, and Lisman's house was in disarray when police arrived. Neighbors said they had heard the two fighting over the weekend prior to his mother's death.
Lorey said police were called to the home by a neighbor who went to check on Lisman after she wouldn't pick up her phone. He said Lisman borrowed the rifle used to kill her from a neighbor to keep animals away from her garden.
Fulton County's DA said in 2013 that Dibble is also accused of stealing some of Lisman's jewelry and other items to cash in for money.
Dibble was found guilty of Murder in the Second Degree, Criminal Possession of a Weapon in the Third Degree, Two Counts of Criminal Possession of Stolen Property in the Fourth Degree and One Count of Criminal Possession of Stolen Property in the Fifth Degree.
Dibble could face up to 25 years to life in state prison when convicted. Sentencing is set for June 12.