The Witness on Netflix: who was the killer, and why it took 16 years to catch him

Here's what happened, who did it, and why the whole thing dragged on for sixteen years.

The crime

On 15 July 1992, Rachel Nickell — 23, a young mother — was walking on Wimbledon Common in south-west London with her two-year-old son Alex and their dog. She was attacked in broad daylight, stabbed 49 times and sexually assaulted. Alex was found clinging to her, trying to wake her up.

Who killed Rachel Nickell?

Robert Napper. A serial offender who had been attacking women across south London for years. By the time he was linked to Rachel's murder, he was already in Broadmoor high-security psychiatric hospital for the 1993 killing of Samantha Bisset and her four-year-old daughter Jazmine.

In 2008, Napper pleaded guilty to Rachel's manslaughter on the grounds of diminished responsibility. Sixteen years after the crime.

Why sixteen years?

Three catastrophic failures, essentially:

• Wrong suspect. Police became obsessed with Colin Stagg, an unemployed local man who walked his dog on the Common. He matched a psychological profile. There was zero forensic evidence against him. Didn't matter — they went after him anyway.
• A honeytrap that backfired. An undercover policewoman posed as a romantic interest to try and lure Stagg into confessing. A judge threw the whole thing out in 1994, calling it an attempt to incriminate rather than investigate.
• While all of this was happening, Napper was free. He went on to murder Samantha and Jazmine Bisset in 1993. That crime could potentially have been prevented.

It took a cold case review and advances in DNA technology years later to finally match Napper to the Wimbledon Common scene.

André and Alex

Rachel's partner André Hanscombe raised Alex alone. Media pressure eventually drove them out of the country — they moved to France. Both served as consultants on the Netflix production, and the series is largely told from their perspective.

The Witness is streaming on Netflix now, alongside a companion documentary, The Murder of Rachel Nickell.