I would guess that they take the rap not "as part of the job" but simply because there's no dilemma in the first place. Imagine the required scenario: a cop telling an admitted serial killer "Look, you're a small fish. If you can give us someone who's really worth our time, we can make life a lot easier for you."
First of all, that already seems like a dubious proposition. Really, they're going to give him immunity for all the people he murdered in exchange for information and cooperation? I guess maybe, but they sure as hell aren't going to publicize that fact.
But before you even get to that point, the cops have to find a suspect who admits to being a hit man. If I were a hit man, probably the last thing I'd say to a cop upon being arrested for murder would be "Oh, don't worry, I do this for a living." If you look at the risk and reward, the almost certain odds of being charged with even more murders are going to outweigh the slim odds that the cops want to lighten your sentence in exchange for cooperation.
So the only group of hit men that leaves who might be willing to confess are those who are already serving life sentences, or are on death row. But we have to filter the life sentences down even more to life without parole, since I think admitting to a past career in assassinations might look slightly iffy to a parole board.
If you have life without parole, I can still think of plenty of plausible reasons that you wouldn't want to admit to being a hit man.
First of all, that already seems like a dubious proposition. Really, they're going to give him immunity for all the people he murdered in exchange for information and cooperation? I guess maybe, but they sure as hell aren't going to publicize that fact.
But before you even get to that point, the cops have to find a suspect who admits to being a hit man. If I were a hit man, probably the last thing I'd say to a cop upon being arrested for murder would be "Oh, don't worry, I do this for a living." If you look at the risk and reward, the almost certain odds of being charged with even more murders are going to outweigh the slim odds that the cops want to lighten your sentence in exchange for cooperation.
So the only group of hit men that leaves who might be willing to confess are those who are already serving life sentences, or are on death row. But we have to filter the life sentences down even more to life without parole, since I think admitting to a past career in assassinations might look slightly iffy to a parole board.
If you have life without parole, I can still think of plenty of plausible reasons that you wouldn't want to admit to being a hit man.