Why do NPCs randomly die or get injured? What mod?

[ltknight88]

I have noticed some NPCs will suddenly "get attacked" or assassinated by what seems like an invisible attacker.

I've noticed it 3 times now. All attacks happened in Whiterun. Once on Danica Purespring, who was injured and went into a bleedout state.

The second was on Acolyte Jenssen is a Nord priest at the Temple of Kynareth in Whiterun.  and he died.

And the Third just happened today, and killed Saadia in the Bannered Mare.

 

It seems to happen after Sex scenes. 

I'd used the SexLab trainer mod. Danica had just used sex to Train up my Restoration skill, when Acolyte Jenssen was killed.

 

I don't know why Saadia was targeted or killed.

 

I used both "Detect Life" and Detect Dead spells, but no extra NPCs show up.

 

I noticed it happening after I loaded SLab Trainers and SLab Solutions.

 

Does anyone know of a mod that either adds this assassin or feature or bug??