By Elisha Fieldstadt, NBC News
An 85-year-old man admitted to killing his adult grandson shortly after he shot him?in their home in, Nashville Tennessee, on Monday, police said.
Ben Phillips? grandmother called local?police around 6 a.m. to report that her husband, John Watkins, had shot their grandson, officials said.
Police arrived and found Phillips, 30, dead in his bedroom with a gunshot wound to the head, according to the release.
Detective John Crumby said Watkins admitted that he shot his live-in grandson while the young man was sleeping.
Watkins has been charged with criminal homicide, local?NBC affiliate WSMV reported.
Tennessee police told the station that Watkins was taking medication for memory loss and they suspect he may suffer from dementia.
Investigators determined “there had been some prior issues going on between him and the grandson, and maybe the memory loss made him think it was recent,” said Nashville police Lt. John Drake.
Watkins told Crumby his grandson caused problems for the elderly couple and was ?constantly threatening? them.