Glen Birdow said his brother claimed people were coming to kill him and that someone had stuck him with a needle.
Nevertheless, he refused to get help.
Police subdued Derrick Birdow with a Taser while he was beating Rev. Danny Kirk, Sr.
Birdow died later, but the exact cause of death was still under investigation Tuesday.
"I don't even know Pastor Kirk," Glen Birdow said. "I'm sorry for his family and everything they're going through but that was not my brother.
"That was somebody else and I hate that."