Polices ask to the people the features of the criminal, then, the police goes to a computer program, where the policeman describes the criminal features to the computer worker, then the computer worker obtain the face of the criminal by setting the program and now the part that you are interested.
There’s an especial team on the police who basing in the computer model obtain the faces of the possible criminals, then they call to the witnesses and they select the most similar face, finally police identificates and locates the criminal, proceding to her/his arrest