Forensic science in criminal investigations began with the identification of blood types found on the crime scene. For cold cases that retained evidence, there's a world of hope that decades-old mysteries can be solved. Forensic science in the 1970sForensic evidence in the 70s relied heavily on the presence of blood at a crime scene. The case marked the first time a cold case crime was solved through the use of forensic genealogy. More than 600 cold cases have been solved with the use of forensic genealogy, according to the Sherry Black Foundation.