Case study: Rachel Nickell

In 1992, Rachel Nickell was brutally murdered on Wimbledon Common in London, leaving her two-year-old son unharmed but clinging to her lifeless body. The initial investigation yielded no immediate suspects, and surprisingly, no forensic evidence, including Rachel's DNA.

Unfounded suspicions and a failed "honey trap"

Upon further investigation and several interviews, one suspect appeared, Colin Stagg, although there was no actual evidence indicating his guilt.

The police set up a controversial "honey trap" operation, hoping to elicit a confession. Stagg, however, never admitted to the crime and was arrested in 1993. The entrapment evidence was later excluded, leading to Stagg's acquittal in 1994.

Forensic Alliance and Operation Edzell

In 2002, the Forensic Alliance launched Operation Edzell to reexamine cold cases, including Rachel Nickell's murder. The team, led by Roy Green, focused on chemistry, hair, textile fibers, and DNA analysis, with April Robson as the lead forensic examiner.

The breakthrough: DNA analysis and shoe impressions

Clothing samples were meticulously examined, and a reconstruction highlighted areas the perpetrator likely touched. A new DNA testing approach revealed a mixed profile, leading to a two-year effort to clean up and concentrate the samples. The DNA, ultimately matched Robert Napper, a man already incarcerated for another murder.

Investigator Roy Green noted similarities between Napper's modus operandi and the Nickell case. Footwear marks collected from the crime scene, slightly smaller than Napper's shoe size, were re-examined. An experiment replicated the mud suctioning effect, explaining the size difference.

The verdict

In 2008, Robert Napper pleaded guilty to the manslaughter of Rachel Nickell due to diminished responsibility. Diagnosed with Asperger's syndrome and paranoid schizophrenia, he received an indefinite sentence at Broadmoor Hospital.

This case underscores the vital role of DNA analysis and the dedication required by forensic scientists. It also highlights the danger of fixating on one suspect, as the initial focus on Stagg delayed the investigation into Napper, emphasizing the importance of thorough and unbiased forensic work.