The family of a teenage girl murdered exactly 20 years ago have appealed for a convicted child killer and rapist to give up her remains.
Arlene Arkinson went missing after attending a disco in Bundoran, Co Donegal, in August 1994.
There has only ever been one suspect connected to the case – convicted child killer Robert Howard, who was acquitted of her murder in 2005.
The jury did not know that by then he was already serving life for raping and killing 14-year-old Hanna Williams from south London.
Arlene's body has never been found. Now, on the 20th anniversary of her disappearance, detectives investigating the murder have made an appeal about specimens of blood belonging to two mystery women found during a search in 2012.
They are also conducting new land searches in Tyrone.
Arlene's sister Kathleen said the past 20 years have been "torture".
She said her family can barely sleep for thinking about Arlene and appealed for anyone who knows anything to come forward.
She said: "I don't know how they are walking about. How they sleep. We haven't really slept properly in 20 years, they need to get it off their chests.
"And it's in around the Castlederg area that they are holding information.
"I would appeal to them to get it off their chest so we can find Arlene and give her a decent burial, as she deserves. And I appeal to Howard again to give up the remains."
Kathleen said she can't put in to words the pain of the past 20 years.
"We've done everything in our power and we just hope that the samples of the blood, that whoever it belongs to, that they come forward. It's been torture. Just pain and sleepless nights."
Kathleen said they are definitely not going to give up.
She said: "I do believe that Arlene will be found, but the police should have acted more quickly back in 1994."
She added: "Sometimes, as the searches were going on, you would have had hope and then it faded. But you still had to keep going."
The officer now leading the investigation, Detective Superintendent Karen Baxter, said the blood specimens were not those of Arlene, but neither are they registered on the national DNA database.
She said: "On the 20th anniversary of Arlene's disappearance, I would ask that any woman who was in this flat, at 49a Main Street, which has since been demolished, at any time to make contact with police.
"They have a story to tell and we want to hear it. Their assistance could be beneficial to the investigation." She added: "This investigation will continue. It will be progressed as far as we can take it.
"Indeed, I can confirm that our inquiries have involved detectives interviewing a man in England.
"While we acknowledge the pain this causes to Arlene's family, police alone cannot solve this case or find Arlene.
"It is only with the help of the public that the person responsible will be brought to justice and the Arkinson family will find any degree of comfort."
The special incident room number to call is 028 7137 9783