The husband of a census worker who was shot dead while collecting forms has put up a £20,000 reward for help to catch her killer.
Mother of one Joanne Mathers, 29, was gunned down on a doorstep 31 years ago in one of the most shocking murders of the Northern Ireland troubles.
She was attacked by a masked IRA gunman in the Gobnascale area of Londonderry on April 7 1981 as she was helping a householder complete a census form.
At the time, republican terrorists had been targeting census workers in a bid to disrupt the survey.
Her husband, Lowry Mathers, said he had put up the financial reward through independent charity Crimestoppers in a bid to finally get justice.
"I want justice for Joanne, even after all these years," he said.
"I hope the reward will encourage someone with information to come forward and tell Crimestoppers what they know."
The money will be paid to any individual who passes on information anonymously that leads to the arrest and conviction of those responsible for the murder.
Mrs Mathers' son Shane, who was just two-years-old at the time of her death, said: "I never really knew my mother because she was taken away from me far too early.
"The person or persons who killed her will never know the pain my dad and I have gone through over the last 31 years, which is why this reward is being put up.
"While our family appreciates that nothing will bring my mum back, we want those responsible for her murder to be found and brought to justice.
"I am reaching out to anyone who might have information to contact Crimestoppers anonymously, because it might be key in helping to catch those who committed this crime."
A Crimestoppers spokesman said: "Crimestoppers wants to appeal to the public for any information they might have on this murder, no matter how small or insignificant they think it might be.
"In 24 years we have never revealed the identity of anyone who has contacted the charity, and we hope this will be an incentive for people to contact us anonymously and give us the information they have."
Anyone with information on the attack can contact Crimestoppers anonymously on 0800 555 111.