Expectancy effects occur most frequently when ambiguity is greatest [21,23]. Cooley and Turvey [19] point out the challenge for forensic examiners in a laboratory to interpret ambiguous stimuli (e.g., incomplete fingerprint), but that is also true for crime scene investigators. Objects found at the crime scene can be quite ambiguous in that scene. Objects may be interpretable in more than one way, depending on the explanation adopted of what has happened. The expectations about the case and the crime scene cannot only influence the interpretation of the crime scene as a whole, but also what is recognized as evidence and which pieces of evidence are secured. The complex nature of crime scene investigations raises the question if and to what extent, the investigators are vulnerable to expectancy effects.