Mary Gregson

A combination of DNA advances and a determined police investigation helped solve one of Britain's older murder enquiries.

Mary Gregson was killed in 1977 as she walked along the towpath of the Leeds-Liverpool canal in Yorkshire. She had been attacked, sexually assaulted and strangled before her body was dumped in the river. Mary had been on her way to work and her husband contacted police when she failed to return home. Her body was found the following day.

At the time of the murder, semen stains found on Mary’s clothing were subjected to blood grouping tests, as DNA profiling was not available. West Yorkshire Police interviewed more than 8,500 people. Forty seven-year-old van driver, Ian Lowther was one of the people interviewed but at this time there were no clues to suggest that he was the killer. He had an alibi for part of the time and had never come to the notice of the police. He had been working as a labourer on a construction site next to the Leeds-Liverpool canal. Despite the huge inquiry, Mrs Gregson's death remained a mystery.

In 1985 single locus profiling (SLP) was attempted on the stain, but this proved unsuccessful, because there was not enough DNA of sufficient quality to obtain a profile. Further advances in 1995 allowed a more sensitive test to be conducted on the same stain but again these tests were unsuccessful.

A cold case review was initiated in late 1997. FSS scientists examined clothing and belongings, while tapings from the original examination were searched for foreign hairs. All of Mary's clothing tested negative for possible DNA material, and so a speculative slide was made from material between two areas of her underwear which had previously been cut out for blood grouping and early DNA profiling methods. Sperm heads were found on the slide from this area. A decision was made to send the rest of the knickers to the specialist DNA Low Copy Number (DNA LCN) unit to maximise the chances of obtaining a DNA profile.

The FSS has a continuing programme of research aimed at improving the extraction and sensitivity of DNA profiling tests. In early 1999 FSS SGMplus™ was launched along with other improvements which have been termed DNA LCN. This has provided the FSS with the most sensitive technique yet. It facilitates the production of DNA profiles from just a few cells and from old, degraded samples. FSS scientists managed to obtain a full male profile from Mary’s underwear using DNA LCN.

Detectives from West Yorkshire police then undertook an intelligence-led screen of the men involved in the original inquiry, and Lowther provided a sample. This sample matched the profile obtained from Mary's clothing. He was arrested in April 2000 and charged with Mrs Gregson's murder.

On 29 September 2000, Ian Lowther pleaded guilty to murder at Sheffield Crown court and was sentenced to life imprisonment.