Newly release footage of the arrest of Derrick Scott, 42, in Oklahoma City last year shows the man repeatedly told officers he couldn't breathe.
He later died in hospital.
In the May 20, 2019 arrest, captured on bodycam footage, three officers can be seen restraining Scott who repeatedly asked for his medicine and said: "I can't breathe."
At one point, one of the officers, Jarred Tipton, replied: "I don't care."
"You can breathe just fine," another officer said a couple of minutes later.
Scott appears unresponsive a few minutes into the footage and was later pronounced dead in hospital.
The cause of death in the autopsy is listed as a "collapsed lung".
Scott was found to be in possession of a gun after police were called to the area south of downtown Oklahoma City that day.
He tried to run from police officers who manage to tackle and restrain him.
Once he became unresponsive, an officer tried to administer CPR while waiting for paramedics to arrive.
His autopsy said police did not cause "fatal trauma" and listed other "significant" factors that contributed to his death, including the use of physical restraint, recent methamphetamine use, asthma and heart disease.
An investigation into the three officers - Tipton, Ashley Copeland and Sgt Jennifer Titus - cleared them of any misconduct.
Oklahoma City police Capt. Larry Withrow told local media Tipton's comment were made in the "heat of a conflict".
"Certainly that may be something an officer says," he said. "Just understand — the officers are fighting with someone at that point."
However, local activists believe justice needs to be done.
"There is a lack of a focus on humanity and civility," said Rev T. Sheri Dickerson, of Black Lives Matter OKC.
Authorities only released the footage after the group included it in a list of demands to city leaders, in the wake of George Floyd's death.