NPC backstory ideas for a murder mystery

Following up a bit on a previous post I made here: https://old.reddit.com/r/DMAcademy/comments/1bq0q3g/tips_for_running_a_murder_mystery_miniarc/

I am looking to run a murder mystery for my players, and after receiving a lot of helpful advice in the first post, I am hoping to take the angle that all the possible suspects have something to hide so that they're all a bit suspicious. However, I'm terrible with developing NPC motivations and backstory. What are some possible reasons that friends of the governor of a medieval port city-state could possibly want him dead?

The one idea I have so far is that one of the suspects is in love with the fiance of the victim.