Shortly after one woman’s murder, the police investigation was curtailed when the crime scene was set on fire, destroying any evidence at the scene. A doctor examining the victim's burned body noticed her right hand had shorter fingernails. When police arrested the arsonist and brought him in for questioning, he had small bruises around his left hand that a doctor surmised were made by someone with short fingernails trying to hold off his left wrist. He became the prime suspect, and this fingernail evidence led to his murder conviction.
In 1994, animal DNA was used for the first time to solve a crime. When a woman mysteriously disappeared, her remains were not found until several months later. After continued searching, the police found a leather jacket in the woods with her blood on it as well as white hairs embedded into the jacket lining. Testing revealed that the hair wasn’t human; it had come from a cat. This initially discouraging result led to a suspect: the victim’s ex-boyfriend, who had a white cat. Testing the hairs for the cat’s DNA — the first such test in history — revealed a match. The jacket was proven to be the ex-boyfriend’s, and he was convicted.
A woman told the police her baby was kidnapped by a masked man and found dead. The woman and her husband later had another child that was similarly kidnapped and found dead, so they reopened the case. The woman had claimed the kidnapper bashed her head with the back of a gun and knocked her out. She said she did not regain consciousness until her husband came home an hour later and woke her up. But a doctor on the case knew her story was impossible: With a head injury of that intensity, she wouldn’t have remembered the intruder or the situation at all. The doctor said that the head injury, if real, would have made the woman groggy, disoriented, and confused. This medical evidence was enough to prove her guilt.