A 5-year-old boy called 911 to report that his mother had collapsed in their apartment, but an operator told him he should not be playing on the phone, and she died before help arrived.
The family of Sherrill Turner, 46, does not know whether a swifter response could have saved her life, but relatives want to know why the operator apparently treated the call as if it were a prank.
Police said the 911 response was under investigation.
Turner's son, Robert, placed two calls to 911 after his mother collapsed Feb. 20 on the kitchen floor. During one of the calls, an operator said: "You shouldn't be playing on the phone."
In a tape of the call, parts of which were broadcast by Detroit-area television stations, the operator said: "Now put her on the phone before I send the police out there to knock on the door and you gonna be in trouble."
In an audio of the tape played on TV, some of what the boy says is unintelligible.
Delaina Patterson, the eldest of Turner's 10 children, said police did not arrive until three hours later. She said only Robert and his mother were home at the time.
Detroit police spokesman James Tate said it was at least an hour before authorities arrived, but he said he did not have details. By that time, the boy's mother had died, he said.
"The operator may have believed he was playing on the phone," Tate said.
Police Chief Ella Bully-Cummings said it was important not to rush to judgment.
"If disciplinary action is recommended following the completion of the investigation, then that is the course that will be taken," she said.
The 911 operator remains on the job amid the investigation, Tate said.