That was the plea entered Monday by 55-year-old Phillip Clark during a court appearance in Bangor.
Clark was arrested last month for the shooting death of Renee Clark, 49.
She lived in an apartment next to Clark and was in the process of moving out when the shooting took place.
She had become estranged from her husband and told authorities she feared her brother-in-law might harm her. Despite that, officials refused to grant her a protection order.
According to court records, clark confessed he shot his sister-in-law multiple times before reloading and shooting her again but he now is pleading not guilty and is being held without bail.