Miss Parkinson, a waitress, 22, of Stevenston, Strathclyde, was killed at Salcombe, Devon, on 20 July. Detectives said that forensic science tests have established a link between her murder and the attack on Muriel Harvey, 67, in Ludlow, Shropshire, on Christmas Day 1992.
Police from Shropshire, including Det Supt Barry Gutteridge who led the rape inquiry, travelled to Devon to work with the murder team in a special unit.
John Evans, Chief Constable of Devon and Cornwall, said: 'Both incident rooms are now operating at full stretch and many lines of inquiry are being explored.'
Police were particularly anxious for information about a man pictured on a security video in the shop of the Castle Street garage in Ludlow late on Christmas Eve 1992. He was described as white, in his mid-twenties, 5ft 6in tall with dark hair and wearing a shortish jacket with leather on it and a woollen hat pulled down over the hairline.
Mrs Harvey, who runs a family business in Ludlow, was raped at 1.30am on Christmas Day as she returned home from St Lawrence's parish church by a man who warned: 'If you don't stop screaming, I'll kill you.'
After the attack, Mrs Harvey, a church warden and former magistrate, decided to waive her right to anonymity, hoping it would help her assailant be caught.
Yesterday, Mrs Harvey's son, Roger Curry, 28, said that his mother was on holiday touring the south coast.
Mr Curry said that when he told her over the telephone that DNA tests had linked her rape with Miss Parkinson's murder she was 'very calm, and her feelings were that she was just terribly sorry for the young girl'. He said that he worried about the danger for his mother when she went public, but 'after the initial anger she had to forgive him and as much as anything she wants him caught so he can receive help for himself'.
An information hotline has been set up at the Devon and Cornwall force's Exeter headquarters on 0392 451090.Reuse content