Rachel's toddler son witnessed the horror

On 15 July 1992, part-time model Ms Nickell, 23, had driven from her home in Balham to go for a walk on Wimbledon Common with her two-year-old son Alex and their family dog Molly.

At a secluded spot, she was sexually assaulted, stabbed and had her throat slit. When her body was discovered by a passer-by, Alex was found clinging to her pleading: "Get up mummy." The boy had tried to stem the bleeding, placing a piece of paper on her forehead.

At the time, police thought the paper highly significant, possibly placed by the killer in a sign of a ritual.

The killing sparked one of Scotland Yard's largest manhunts. In all, 32 men were arrested and 548 suspects ruled out. Only with Robert Napper's conviction today can her family even try to gain closure.

Her parents Andrew and Monica, who raised their daughter in the Home Counties, now live in Staffordshire; a brother is a vet in south London.

Ms Nickell was encouraged as a child to take exercise, going for long walks in the country or swimming. It was at Richmond pool that she met Andre Hanscombe, a semi-professional tennis player and coach who took a job as a motorbike messenger in the City for the regular pay to support the young family. The couple set up home in a flat in Balham but ironically Ms Nickell was worried about local "nuisances" at the nearer parks of Clapham Common and Tooting Bec and chose to drive to Wimbledon Common instead.

After the death, Mr Hanscombe moved to France, taking Alex with him and hoping he would grow up as normally as possible away from the intense interest of the media. It has not been an easy transition. Alex is 19 now; his father, offering a rare insight, once described him as a "brooding, moody teenager".

A decade ago the pair moved to a town in north-east Spain. Home is now a three-storey end-of-terrace house on the outskirts of the town in pine tree-covered hills. British expats are few and far between.

Alex attended the local secondary school until two years ago and speaks three languages fluently- English, Spanish and Catalan. His friends are all locals but he and his father appear to have kept the killing a secret from their neighbours.

One said: "Alex and his dad are friendly and popular but have always kept themselves to themselves. Alex is a keen runner and I often see him out running. No one round here knows anything about Alex's mum or the family's background."