A detective struggles to find his partner’s killer uncovers other murders and two dirty cops on his trail and the possibility it was an inside job.

Consider restructuring the logline so it starts with the inciting incident and finishes on a clear goal. You describe the MC's descovariesin the story but not the MC's actions and goals.

Also, posibilities should be left out of a logline - either it was an inside job or it wasn't. Best to be more definitive with story elements in a logline than indicative.

For example:
After his partner is killed, a detective uncovers a plot by dirty cops and must prove their guilt to stop another murder.