“We always knew with fair certainty that two men had been involved.  First of all two men had been seen with Helen and Christine in the pub.  Secondly killing these two young, fit girls was not a job that one person could undertake” Tom Wood But forensic scientist Lester Knibb couldn’t find the evidence to prove that theory. The development of DNA profiling only seemed to scientifically suggest what common sense said couldn’t have happened – that only one man was able to separately rape and strangle two young women.  “The very early DNA profiles we got were for one man and of course when we got the profiles of that one man...I remember sitting in the office...sitting back thinking, only a matter of time you know...because (at) that time the DNA databases were starting to be produced throughout the world.”Tom Wood, Former Det. Chief Constable, Lothian & Borders Police But even the one profile they had, didn’t match. It seemed inconceivable given the brutal nature of the crimes that person hadn’t offended before. It was 2004 before the next breakthrough. New technology allowed the profiling of the Y chromosome. This meant they could now match profiles of men who were related to each other, such as fathers, sons, brothers and uncles.But in order to extract this profile, they would require a piece of evidence to have been kept from the crime scene for 27 years.Thankfully, that’s exactly what Lester Knibb had done.A small square of material from Helen Scott’s coat was still sealed in the freezer in the back of his lab.“So I took a small extract from some of the original staining.  I tested them for the enzyme acid phosphatase, which is something which is present in high concentration in semen and that gave a positive result.” Armed with this, detectives were able to begin searching for the Y chromosome. But it also revealed what detectives had suspected all along: The presence of another killer. “...there were two male DNA samples on that piece of coat that had been kept all those years.  One that we’d known about and one that was so faint that only modern technology would bring to the fore.”Allan Jones, Former Det. Superintendent, Lothian & Borders Police When the second sample was put into the database, a name came back...Angus Robertson Sinclair.