any Ideas of what I can write for a murder mystery?

somebody trying to cover up their business of smuggling immigrants and selling them for parts (organs) - maybe gutted bodies start turning up

Oh! write a novel where no one knows what killed someone, and it turns out it was simply pollution, and then everyone wonders why no one is brought to justice about it. You could do 9/11 and the false EPA reports.

On a less political note - rent the movie Gosford Park - its a great murder mystery.

Set the novel in a place you know, it's the easiest.

Finish The Mystery of Edwin Drood by Charles Dickens - or just re-write the whole thing with new settings. Just kidding!

maybe something about an inheritance from a rich old great uncle or something. keep killing characters off every so often. include faked deaths, traps, accidents, murder, etc. but never reveal who did it until the end

You have to write about things you know - otherwise it will lack emotion.

What would make you murder someone - what niggling annoyance makes you fly off the handle where everyone else seems to be unbothered?

somebody just asked, whatever happened to the taco bell dog? he could be kidnapped and put thru ritual sacrifice, his bloody mangled corpse, found beneath the foundation of a KFC