Brian Blackwell, Liverpool, UK
The 18-year-old was considered a model student. However, in 2004, after a row over money with his parents, Sydney and Jacqueline Blackwell, Brian snapped.
He battered his father with a claw hammer and stabbed him 30 times with a 10-inch carving knife, before knocking his mother Jacqueline unconscious and stabbing her.
Brian escaped to New York with his girlfriend Amal Saba, 17, using his dead father’s credit cards to pay for a suite in a five-star hotel. He told Saba the cash was from a £70,000 tennis sponsorship deal. He was convicted of manslaughter on the grounds of diminished responsibility and jailed for life.