Investigators say Larry Sharp and his sister were arguing in their mother's hospital room when Sharp grabbed the sister's gun and threatened to shoot her.
The incident prompted a lockdown of the hospital as law enforcement swarmed the area.
The criminal complaint says the two were arguing over who should have power of attorney over their mother.
Sharp then allegedly punched his sister several times in the head and pushed her into a chair.
He did not fire the gun, but left it on a table outside of the room as he left. Sharp was arrested at his home a short time later.