Consider now the position of the investigator. To use the same, rather facile example, he is more in the position of someone who is assembling the jigsaw without the aid of picture. Like all similes the jigsaw one is not perfect. It could perhaps be refined by saying that the pieces are re-cut into random shapes and sizes each time the game is played, and that some pieces are always missing, and that an essential step is to elect whether the picture built up is sufficiently like some other picture to enable the proposition that they are the same. This represents the point where the investigator has to make up his mind if he has enough evidence to go to court.
Criminal investigation is a high-grade intellectual pursuit.
It is lawful search for people and things useful in reconstructing the circumstances of an illegal act or omission and the mental state accompanying it. It is probing from the known to unknown, backward in time, and its goal is to determine the truth as far it can be discovered in any post-facto inquiry. The most prominent feature of crime investigation, as a course of human action is intuition. This is not to deny the value of system and precept, but to indicate at the outset the central position of this natural, but most profound and mysterious, function of the human mind in the work of investigator. Many scientists are uncomfortable with the idea that even their most precise procedures originate more from intuitive leaps of the imagination than from explicitly describable method.