When Arlene Fraser vanished without trace after waving her young children off to school, detectives had a suspect with a motive - but precious little else. Her husband Nat was a jealous and violent man who had been accused of attempting to murder Arlene just five weeks earlier. Their marriage was on the rocks, and on the day she went missing Arlene had been due to meet a solicitor to discuss a £250,000 divorce. But when police started to investigate, they found what one officer described as "a daunting absence of clues". No crime scene, no signs of a disturbance, no forensics, no eye witnesses, no CCTV. Arlene's empty bungalow in Elgin, in the north of Scotland, was compared to the Mary Celeste. The house was unlocked, the ironing board was out, the hoover plugged in, washing was hanging on the line outside, the medication she needed for Crohn's disease had been left behind.…