Free to good home: one Idea, housebroken but needs grooming

Talking with an acquaintance yesterday about what must be the odd search history of writers' computers, I had an idea.  I know it's not the most original, but I think it would be fun in the right hands.  Since it's not my style, I thought I'd put it up for adoption on here.  

What if an author of murder-mysteries became a killer him/herself and was able to use his/her stories as a cover?  Maybe the author was always fascinated by death/murder and found a natural outlet in writing stories/novels based on the subject.  For atmosphere and ideas they frequent bad areas, places that often turn violent, locations of notable past murders.  They research every facet of every stage of the crime, take courses in crime scene processing, speak often with attorneys and police about procedures, investigation, the justice system in general.  They learn all the tricks of the trade to keep their writing real and accurate.  They publish a few novels, or maybe several, with at least enough success to write full-time.  But at some point writing becomes "not enough" and they want more, even if just sub-consciously at first.  When a series of innocuous events lays the opportunity for a perfect murder in their lap, they seize it.  Immediately afterward there is regret, fear, self-loathing, but not enough to go to police.  The author covers up the murder, out of self-preservation if nothing else, and continues their normal routines even under constant worry of being discovered.  But as far as the rest of the world is concerned, there never was a murder, and the author isn't outed.  Once the fear subsides, the author has to admit it was a singularly thrilling act.  Before long, they are looking forward to the next opportunity.  And how do you catch someone who already "kills" for a living?

I would love to see this idea given a good home, raised up by a firm but loving hand, and allowed to mature.  And if it gets published, I expect 15% royalties.