I thought it was established that he had a second mistress.
Two days before their deaths, Kazemi(girlfriend) was pulled over in a Cadillac Escalade in Nashville. McNair was the passenger and Vent Gordon, a chef at a restaurant McNair owned, was in the back seat. The vehicle was registered in the names of both McNair and Kazemi. She was charged with driving under the influence of alcohol.[37] McNair was not arrested, instead leaving in a taxi with Gordon, despite Kazemi repeatedly asking the arresting officer to tell McNair to come to the police car to talk to her. However, McNair later bailed Kazemi out of jail.[49] The police later stated that after being released from jail, Kazemi purchased the gun from a convicted murderer she met while looking for a buyer for her Kia.[50]
More likely a gambling related hit on Mcnair and girlfriend just a loose end cleaned up. A a
When big money or politics are involved investigating can be compromised. Then there is also incompetence and laziness.