I am surprised that Scratched had not been the title of a book - to the best of my knowledge. I think Scratched is appropriate in a mystery thriller for my reasons including what I hope will be definitions included in the friend piece of the book. That is, I find it to be a very unusual word. First, it can be a verb and generally mean that one has scored or marked the surface of something with a sharp or pointed object. But then, does the object making the scratch have to be sharp? For Instance, we say things like "she scratched at her nose to relive itching." As a verb, it could also mean "quick writing." In other words, "scratching out something." It can also mean to remove something by pulling a sharp implement over something else.
It can also be used as a noun as in "scratching" or the sound of "scratching." Perhaps more pertinent is that "scratching" or "scratches" can be used to indicate something has been accomplished with great effort or difficulty, "completely from scratch." Or, it can mean something was stricken as in a writing so that something was "scratched out." And that gets us to a withdrawal from a competition such as a horse being "scratched" from a race and something cancelled or abandoned such as an undertaking.
Then, again, from sports, in golf, "scratch" is a handicap of zero which means that a player is good enough to achieve par on a course. And also relevant to pool is that "scratch," informally, means money. And of course, in pool it means that the cue ball has found its way into a pocket.
"Scratched" is also found in familiar phrases such as from the very beginning, meaning without having prior experience or talent or assistance. And Lord knows, I have scratched my head from time to time to come up with the right word or phrase or solution. I always wanted to scratch beneath the surface of my characters, and at the same time, I know that I have sometimes not been up to scratch. Like monkeys, I have scratched someone else's back with the hope that they will scratch mine, used a "scratch" pad, had a "scratch" test for an allergic reaction, and so on and so forth.
My tentative title Scratched added to "ed" because it reflects past tense and it is in verb form. I would be interested in other definitions which I have not come across while I scratch out a title with my publisher.