By Shaun Boyd

DENVER (CBS4)– The Denver Police Department is investigating an incident at the city jail that left an inmate on life support at Denver Health Medical Center.

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Sources tell CBS4 investigator Brian Maass that Michael Marshall was acting erratically and tried to run when a deputy at the jail approached him, resulting in a struggle involving several deputies.

Denver Sheriff Department deputies put the 50-year-old inmate in a restraining chair where he continued to struggle and his family says he suffered a massive heart attack.

“And they proceeded to do CPR and they ended up getting a heart rate and blood pressure from him and they continue to give him CPR on the way to hospital,” says Marshall’s niece, Natalia Marshall.

CBS4's Shaun Boyd interviews Natalia Marshall and Brenda Wright (credit: CBS)

CBS4’s Shaun Boyd interviews Natalia Marshall and Brenda Wright (credit: CBS)

Marshall was arrested last Saturday night at the Driftwood Motel in Denver for trespassing and disturbing the peace. His sister says he suffers from paranoid schizophrenia, has been in and out of jail and has lived on the street for years.

“We’ve tried our hardest to get him programs and get him help but he’s one of those people likes being where he is. I know my brother has some problems but he wasn’t harmful,” said Marshall’s sister Brenda Wright.

Driftwood Motel (credit: CBS)

Driftwood Motel (credit: CBS)

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Wright says the family just wants to know what happened at the jail. They found out about the altercation with deputies on CBS4 News.

Natalia Marshall says they believe his mental illness played a role in what happened, “What I would like to know is officers knew about that and how they respond to someone like that, to someone who has a mental disorder. The only thing we do know is there’s an investigation. We don’t know if there’s any wrongdoing we don’t know if it was aggressive to point that it was what caused his cardiac arrest.”

Marshall’s sister says he’s one of five kids and the family is by his side now.

“I know he’s never had any heart problems so I don’t know. I just want answers. That’s all I want is answers,” said Wright.

CBS4's Shaun Boyd interviews Natalia Marshall and Brenda Wright (credit: CBS)

CBS4’s Shaun Boyd interviews Natalia Marshall and Brenda Wright (credit: CBS)

The sheriff’s department says that in addition to an investigation by Denver police, the Independent Monitor has been contacted and an internal review will be conducted. There is video of the incident.

This is the latest in a series of issues plaguing the Denver Sheriff Department.

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Shaun Boyd is CBS4’s political specialist. She’s a veteran reporter with more than 25 years of experience. Follow her on Twitter @cbs4shaun.