locard exchange principle,“every contact leaves a trace".
I think this principle is only applicable to crimes like theft,robbery, burglary etc and in some instances in murder but I don't think that this principle can be applied to cases related to fraudulent checks,cyb:er crime and many other violent crimes such arson and narcotics.
it is the technique for crime scene investigation only,while investigation encompasses many stages I.e interview and prosecution



and thanks for the complements