Timothy Lee says a 911 operator did not initially alert police that Daniel Markel had been shot after receiving a phone call from one of the man's neighbours.
Audio of the call was released Thursday by the Tallahassee Police Department.
Lee says a review showed the 911 dispatcher categorized the call as someone being incapacitated, which could have resulted in a delay in when police and paramedics arrived on the scene.
Markel — a Florida State University professor well-known in legal circles nationally and internationally — waited 19 minutes for an ambulance to arrive.
He died in hospital 14 hours later from a gunshot wound to the head.
Police have yet to identify any suspects in the case, but have said they believe it was not a random act.
Markel leaves behind two young sons.