Word for the cause of something negative

Question

I am thinking of a word that I have forgotten. It can be used in sentences like; "I believe the [word] here is the incompetence in leadership..."

Basically, it is the cause (or a proposed cause) of something negative. I believe the word has some level of animacy, and for some reason I'm having associations with the word perpetrator and offender. I feel like it's at the tip of my tongue yet so far away.

Answer 1

I just realized what I was looking for.

The culprit.

I believe the culprit here is the incompetence in leadership.

This explains my associations with perpetrator and offender.