When Brenda’s ex-husband, Rex, went into the hospital suffering from pulmonary fibrosis, he gave her medical power of attorney. She claims when they met with doctors, Rex knew he was dying and asked for help with his pain.

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“They agreed to just give him the drugs that would make him comfortable,” Brenda says.

Rex died two weeks later. Despite an autopsy report that determined he died from natural causes, his daughter, Amanda, says she believes he was murdered.

WATCH: Woman Who Claims Circumstances Surrounding Dad's Death Are Suspicious: 'I Won’t Stop Fighting For My Father Until I Get All The Answers'

“You’re making a very serious speculation here that [Brenda] actually asked them to overdose him,” Dr. Phil says to Amanda.

“I think that that is a possibility,” Amanda says.

“Rex died because of natural causes,” Brenda maintains.

In the video above, Amanda explains what she believes happened to her father in the hospital before his death. On Tuesday’s episode of Dr. Phil, a cardiologist weighs in on Rex’s health and death. Will it change Amanda’s opinion of how her father died? Check here to see where you can watch.

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Will Cardiologist’s Explanation Of Man’s Death Change Daughter’s Opinion Of How He Died?