Trying to escape from his criminal past, a neurotic fixer must cover up his connection to a recently discovered stash of body parts, all while battling his own grisly hallucinations.

The structure of a logline should ideally imitate the structure of the plot in the resulting script – inciting incident, main character + flaw then goal. Try re-positioning the discovery of the body parts at the beginning of the logline? then define the MC and describe his goal.

The line about trying to escape from his criminal past can be cut because it doesn’t contribute to a better understanding of the plot all it does it describe the MC as remorseful perhaps just change it to that and let the reader understand what you mean.

Secondly best to define him better tan fixer because it is a slang type description that may be miss understood by some. Most importantly of all though, the logline needs a clear goal for the MC, how does the audience know beyond a doubt that he has covered up his connection to the body parts? What is the obvious visual that will tell the audience just that? Also how will the audience know he has changed as a person?

E.g:
After the discovery of his most recent victims a remorseful mafia henchman must incriminate the mob boss to prevent any further deaths.

Hope this helps.