COLUMBUS, Ohio (AP) — Ohio’s correctional agency found that at least five prison guards used excessive and unjustified force against a Black inmate before he died in custody in February, officials said Tuesday.

Security footage released by the Ohio Department of Rehabilitation and Correction showed Michael McDaniel, 55, collapsing on his own and being taken down to the floor at least 16 times before he died, the agency said.

The department initiated a disciplinary process for six correctional officers, including a supervisor who did not use force, and two medical staffers who took part in the series of encounters with McDaniel on Feb. 6.

One of the medical staffers in question, a nurse, is being investigated for allegedly lying on a medical document that McDaniel refused care, the agency said.

“We’re responsible for what happened in that video,” director Annette Chambers-Smith said Tuesday. “There is no question about that.”

The Franklin County Coroner’s office had declared McDaniel’s death a homicide and ruled the cause as a “stress-induced sudden cardiac death.” The autopsy detailed injuries to his head, face, shoulders, wrists, hands, knees, feet, toes and abdomen. McDaniel also had multiple rib fractures, and the coroner found evidence of heart disease.

A phone call and an email requesting comment were left with the Ohio Civil Service Employees Association, the union representing correctional officers.

Tuesday’s report by the department and Ohio State Highway Patrol first detailed a verbal confrontation taking place between McDaniel, who was in his cell at the time, and a prison guard at the Correctional Reception Center in Orient, a Columbus suburb. Moments later, security footage shows another guard appear and they search McDaniel’s cell — a practice that prison officials say is meant to be random.

The guards then open McDaniel’s cell door and begin to struggle with him before they move to a part of the prison that is not visible by security cameras. The two female guards testified that as they attempted to handcuff McDaniel, he became combative and assaulted the officers.

The report concluded that the search of McDaniel’s cell, which was also performed without a supervisor, was not justified. Officials did say, however, that the guards’ use of force against McDaniel in the initial struggle was justified.

Over the next 23 minutes, video footage shows six more prison guards forcibly take McDaniel to the ground, both inside the prison and outside, in the snow-covered yard, as they escort him to the medical facility for an exam. The majority of the encounters happened as more than half a dozen officers looked on. The department concluded the 16 times McDaniel hit the ground were avoidable and due to neglect of care by the staff handling him.

The report says McDaniel’s medical examination took less than a minute and is also under investigation for the quality of care he may have received. There is no security footage from the exam room.

The report also states the nurse did not do a standard exam or check his vital signs while another nurse signed a form that McDaniel refused medical treatment. The state correction department said McDaniel never refused treatment.

The guards then escorted McDaniel back outside the facility where he collapses for the last time before CPR is initiated and an ambulance is called. He died shortly after.

“This is not what we trained people to do,” Chambers-Smith said. “Not everyone is suited to correctional work and those who are not suited should be removed.”

State prison officials say a nurse and a guard involved in the encounter resigned before the investigation was completed.

The disciplinary process will continue for the rest of the staff. The department said it is moving forward with obtaining more security cameras at all prison facilities as well as outfitting staff with body-worn cameras.

A county prosecutor will make a decision on charges.