Lisman was found dead in her Ephratah home on Mud Road in July 2013. Police said she died of a single gunshot wound to the head.
Sheriff Thomas Lorey said at the time of his 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 on Monday. Neighbors say they had heard the two fighting over the weekend prior to his mother's death.
Lorey says 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 last year that Dibble is also accused of stealing some of Lisman's jewelry and other items to cash in for money.
Dibble could face up to 25 years to life if convicted.