The 1996 Seattle murder of suburban couple Raquel Rivera & Jay Johnson. Investigators first believe the slayings were the result of a drug deal gone bad. However, no drugs are found in the house and the victims' blood isn't present on the clothing of the suspects. Evidence from the couple's dog Chief eventually ties one of the murderers to the scene. One of the first cases where dog DNA was used to convict. (thetvdb.com)