When crime scene investigators arrive at the place of a crime, they first try to make sure the area is secure.

VOA: special.2010.05.05

For example, she discussed how investigators can learn a great deal from the shape of the blood drops found at a crime scene.

VOA: special.2010.05.05

But added they were still "quite satisfied that the scientific support for the assertion that the appellant was the source of the fibres found at the crime scene is compelling".

BBC: Suffolk murder conviction appeal rejected

In some of America's courts this has, to the fury of the forensic scientists involved, led to previously admissible forensic techniques notably handwriting and hair analysis (the examination of features like the colour and microscopic structure of human hair found at the scene of the crime) in particular being deemed unscientific.

ECONOMIST: Whose body of evidence?

If you're the guy in the box out there at the scene of the crime, most in need of the protection, you're flat out of luck.

MSN: December 23: Wayne LaPierre, Chuck Schumer, Lindsey Graham, Jason Chaffetz, Harold Ford Jr., Andrea Mitchell, Chuck Todd - Meet the Press - Transcripts | NBC News