There should be tiers of clues to be found. A Search check done by someone relatively untrained would be able to tell that a victim was killed by a slashing weapon and find a footprint in the blood. A talented investigative could determine that it was a kukri that was used by the shape of the wound, a dwarf by the width of the print, and even the age and make of the boot by the patterns in the print.
For an investigatiion heavy campaign, make it so that some clue is left behind no matter what, even if it's realistic that the criminal cleaned up after himself. Maybe there were witnesses. A single hair left behind. A children's story that has eerie parallels to the case.
I ran a Sharn investigative campaign for about three years now - the Sharn Freelance Police. Most sessions tended to fall into the pattern of set-up, crime scene investigation, following the first clue, minor battle, gaining clues from the fight, following up the second clue, big fight, resolution. Make sure you keep a nice pulpy mix of action and roleplaying/investigation. Don't worry about making the crime scenes too realistic - entertaining is more important.
Demiurge out.