I need some ideas for a mystery story

ok for those of you out there who have sum good ideas 4 a mystery... I COULD REALLY USE SOME!!
THANK you SOOO MUCH!!:D:D:D

somebody killed somebody and people dont know who but theres evidence (hair, clothes, jewlrey, etc,.) that the killer left behind that may help whoever it is thats trying to find the killer find the killer. but then add an unexpected twist like the detective whos trying to find the killer has a split personality and its actually the detective who killed the person.

I stumbled upon this ...and thought it would make a good thriller/mystery and it really happened!

1959: In the Dyatlov Pass incident, Nine ski hikers in the Ural Mountains abandoned their camp in the middle of the night in apparent terror, some clad only in their underwear despite sub-zero weather. Six of the hikers died of hypothermia and three by unexplained fatal injuries. Though the corpses showed no signs of struggle, one victim had a fatal skull fracture, two had major chest fractures (comparable in force to a car accident), and one was missing her tongue. The victims' clothing also contained high levels of radiation. Soviet investigators determined only that a compelling unknown force had caused the deaths, barring entry to the area for years thereafter.

Google it for more info. Good luck