The son of a woman murdered in Sheffield 23 years ago has called for an end to the "secrets" that have protected her killer as a £10,000 reward was offered to help solve the case.

The body of Patricia Grainger, 25, was found near her home in Parson Cross in August 1997.

She was discovered in a brook face down in the water submerged by the weight of a divan bed base.

She had been sexually assaulted before she was strangled and stabbed.

Her family has put up a reward of £5,000, which has been matched by Crimestoppers.

Her son, Danny Grainger, said: "My vulnerable mum was treated in the mostsickening way possible, used and abused as if she wasn't human.

"She had learning disabilities and that made her trusting of anyone who showed her interest. They abused that trust.

"Someone out there knows what happened to Pat. No more secrets.

"No one should be able to get away with such a terrible crime on an innocentyoung mum."

Gemma Gibbs, of Crimestoppers, said: "The account of what happened to Patricia is truly horrendous.

"Whilst many years have passed, her son and family deserve some closure, to see justice done and to have some answers."