Ok. Dottie I seriously appreciate your contribution to my post and first I will answer your questions in order for first asked to last. I'm still in the planning stage of the campaign, so it will likely change with more of your posts.
1) They were hired because of their reputation.
2) I didn't say that they were interested in what looked like a suicide. That was only an example for your earlier question.
3) They aren't investigating one murder only. There are several murders throughout the campaign. Each will get them a little bit closer to the killer(s).
4) I will add in the clue to the murderer myself. That's why I don't want you to put in that clue.
5) They don't know about the fanatic paladins exactly. They were just hired to find out who is doing the murders.
6) The murders all have one thing in common...they were performed quickly and all of the victims did some kind of sin just before they died.
Now I will put in my comments to your suggestions.
The reason there are so many murders (about 200) is because for almost 70 years of the original fanatic paladins life, he killed people. He killed about 1-2 murders every week/month and they were just thought as not being linked in any way. Until recently they have begun to see the connections to those murders and notice similar murders are happening more constantly than they used to. Now they see it as a major threat, rather than several minor ones.
I like the idea about a friend dying, so I'll add that a close friend/investigator that was working on they same case as them gets killed after the first two or three murders they investigate. This would make it more than just a job and make it much more personal. Thanks for the idea

.
Also I would really really appreciate it if you continued to post here

. Any posts, insulting, contributing, or personal modifications/suggestions will be greatly appreciated from anyone.