A squad of 80 detectives interviewed almost 100,000 people

A squad of 80 detectives interviewed almost 100,000 people Joan, of Preston, Lancashire, was drinking heavily, taking drugs and having casual sex to pay for her addictions after two failed marriages.

She was last seen walking the badly-lit streets into the town centre on her way to have a late-night drink just before 10.30pm. Her body was discovered two days later dumped in the ramshackle lock-up garage.

A squad of 80 detectives interviewed almost 100,000 people and took more than 6,000 statements divorced and saliva samples but no arrest was ever made.