Cases go cold when logical leads are exhausted without resolution, evidence or the significance of some information is overlooked, or through confirmation bias. Confirmation bias results when a theory of a crime is hastily formed, and evidence is sought which supports the theory, with contravening information and evidence being discarded 

Cold case analysis is a comprehensive, methodical process of reexamining crime scene photos, evidence, forensic analysis and witness statements to develop an understanding of the crime. The first question to be answered is, “Was the investigator’s theory of the crime consistent with the facts?” Point being, if the theory of the crime is incorrect, the outcome will be wrong. For example, a victim may be found laying on a sidewalk, dead from blunt trauma to the skull, wallet missing. The initial theory may be robbery which could mean it was random victim, while the blunt trauma may indicate the victim was known the offender, with the wallet taken to give the appearance of a robbery. 

Moving forward, every aspect of the investigation is reexamined, looking for the obscure piece of evidence, the potential witness not interviewed, the record or alibi not checked. Issues are identified, and potential leads or courses of actions delineated.