A Hard Ticket Home (Rush McKenzie) by David Housewright

Rush MckKenzie used to be a cop... until he decided to get rich from some insurance money. You can't take a cop out of a man though, that's why he still does some favors for people every now and then.
In this first novel to feature him he tries to track down the missing daughter of a friend. This girl's bone marrow is the only thing that can save her younger sister. Things, however, are soon complicated by pimps, pushers and a serial killer.
The whole favor-thing reminded me a bit of the old TV-show 'Stingray' that I used to love. Several times, like Nick Mancuso used to do in that show he enlists the help of people he did a favor for in the past. It makes sure Rush is up to the job and an okay gimmick when it's not overdone (which it's not in this one).
Rush is refreshingly nice guy. He can sure as hell handle himself in a fight but he still has trouble encountering violent death.
I enjoyed it enough to read the rest of the series.