After his partner?s murder, a suspended detective investigates an unsolved murder believing it?s connected, stumbles onto additional murders, speculates it?s an inside job carried by dirty cops who are now hunting him.

It’s not immidiatly clear what the MC’s goal is. It could be to find his partner’s murder and bring him or her in, but it could also be to catch the dirty cops or solve the other unsolved murders. Best to focus the logline on one primary goal, so which is it that drives your Mc the most?

Seeing as the inciting incident is the partner’s murder, I would wager it’s catching the partner’s killer and the rest are complications that occur in the story proper.
Therefore:
After his partner is murdered, a rebelious detective must fight police corruption to catch the killer before he becomes the next target.