In the 1960s, an unidentified serial killer terrorized London sex workers. The Hammersmith Nude Murders remains one of Britain's most infamous unsolved crimes.

Without a body, proving that someone has committed murder is difficult but not impossible. More than 500 no-body murder trials have been held in the United States, with a conviction rate higher than that of all murder trials.

In today's world, homicide detectives are expected to be jacks-of-all-trades: equally adept at chasing outlaws and identifying DNA evidence at the scene of the crime. But, in an overwhelmingly male-dominated field, Frances Glessner Lee, a Midwestern woman without a high school diploma, made contributions throughout the 1930s and 40s that earned her the moniker 'The Mother of Forensic Science.'

Over the last few decades, a major trend in forensic science has been the rise of doubts about previously rock-solid methods, raising serious concerns about the justice system's ability to protect the innocent and punish the guilty.

Ken Martin, a veteran crime scene investigator, describes problems that arise when gathering evidence, and how to avoid having defense attorneys claim contamination.