(CNN) The storm over the Chicago police's use of force shows no sign of abating.

Hours after the U.S. Justice Department said it was investigating whether Chicago police officers had made a habit of breaking the law in their practices, the city released a video late Monday showing officers using a Taser on a man in a cell and then hauling him out along the ground.

The incident took place in December 2012, and the man shown in the video, Philip Coleman, later died at a hospital after suffering an adverse reaction to an antipsychotic drug.

"I do not see how the manner in which Mr. Coleman was physically treated could possibly be acceptable," Chicago Mayor Rahm Emanuel said in a statement. "While the medical examiner ruled that Mr. Coleman died accidentally as a result of treatment he received in the hospital, it does not excuse the way he was treated when he was in custody."

Mayor: Case isn't closed

The mayor said that either the actions of the officers involved or the policies of the department were at fault -- and that he hadn't received a good enough answer on either point from the former leadership of the Independent Police Review Authority.

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"As a result I do not consider this case to be closed or the investigation into what happened that night to be over," Emanuel said. The city on Monday also released large amounts of other information related to the case, including police reports and 911 calls.

The medical examiner at the time found that Coleman, 38, died from a severe reaction to the administration at the hospital of haloperidol, an antipsychotic drug. But the examiner's report also detailed dozens of bruises and abrasions all over Coleman's body as well as a fractured rib.

A police report said Coleman had been taken into custody on December 12, 2012, on suspicion of assaulting his 69-year-old mother and he also faced felony charges for attacking and spitting on the responding police officers.

Father: Police took 'no helpful action'

The Taser incident in the police cell took place after Coleman physically resisted efforts to transport him to a court building, according to the report. Coleman clashed violently with police officers at the hospital where he was taken for treatment, trying to seize an officer's Taser, it said.

After hospital staff administered a sedative, Coleman calmed down but then began to experience "physical problems," the report said.

"Independent of the facts that led to his arrest or the actions at the hospital, we are held to a higher standard and we must strive to live up to it every day," Chicago Interim Police Superintendent John Escalante said in a statement Monday. "While the independent investigation is ongoing we will be doing our own review of our policies and practices surrounding the response to mental health crises."

Coleman's father, Percy, told the Chicago Tribune on Monday that his son had "a mental breakdown" on the day of the altercation with his mother.

"She called the police to get him some help because she knew he wasn't acting in his right mind," Percy Coleman told the newspaper. "Instead, the police took no helpful action, and they locked him up. And then 12 hours later, he was dead."

Public outrage over 2014 killing

Chicago police have faced public outrage and intensified scrutiny in recent weeks after the release of the October 2014 video of Officer Jason Van Dyke fatally shooting teenager Laquan McDonald on a Chicago street.

People took to the streets to protest what they felt was an excessive use of force and dishonesty by the city and Van Dyke's fellow officers, who initially accused McDonald of threatening officers. Van Dyke has been charged with first-degree murder.

Since then, the city's police superintendent and the head of the Independent Police Review Authority have both stepped down.

Amid the criticism, Emanuel's office has announced a series of measures, including expanding the police body camera program and establishing a task force to review police discipline procedures.