There will be no prosecutions following an investigation into the murder of a German backpacker in Northern Ireland in 1988, it has been announced.

The body of Inga Maria Hauser was found in a remote forest, outside Ballycastle, Co Antrim, 14 days after she was last seen alive on a ferry from Scotland.

The 18-year-old's death in April 1988 remains one of Northern Ireland's most high-profile unsolved murders.

A 60-year-old man and a 57-year-old woman were recently investigated by the PSNI over the killing.

A file was passed to the Public Prosecution Service (PPS) in 2019, which has announced its decision not to pursue prosecutions.

In a statement the PPS said the police file was carefully considered by senior prosecutors but it concluded that there was not a reasonable prospect of conviction for any offence.

It said there was not enough evidence to link the first suspect to the victim and that a lack of clarity around the date of Ms Hauser's death undermined the case against the suspect.

The PPS also concluded there was insufficient evidence to establish that the second suspect had possessed and withheld information that would have been of material assistance to the police investigation.

Deputy Director of Public Prosecutions, Michael Agnew, said Ms Hauser's sister Friederike was informed of the decision this morning via video conference.

"The murder of Inga Maria Hauser causes enduring distress and pain over 32 years later," he said.

"We in the PPS acknowledge the deep disappointment felt today by the family and friends who loved Inga Maria and still miss her.

"The file received by the PPS contained the product of extensive PSNI investigations and was given the most careful consideration by a team of highly-experienced prosecutors. The Test for Prosecution was applied to this evidence, in line with our Code for Prosecutors.

"The standard of proof required in a successful criminal prosecution is high. The PPS can only prosecute a case which is assessed as having a reasonable prospect of conviction. In this case, our conclusion was that the available evidence was insufficient to meet this standard and therefore the Test for Prosecution was not met.

"We have offered reassurance to the family of Inga Maria that this decision was taken only after a most careful and thorough consideration of all available evidence."

The PSNI has said it will continue to investigate to try to bring Ms Hauser's killers to justice.

In a statement, Detective Chief Superintendent Raymond Murray said his thoughts were with her family and he made a renewed appeal for help.

"Our thoughts are with Inga Maria's family today as we know the Public Prosecution Service decision not to prosecute is another difficult milestone in the search for justice for their loved one. However, this decision does not signify the end of the enquiry for police.

"We realise that the PPS gave very careful consideration to the file of evidence and we are grateful for the chance we had to present the case to the PPS and Senior Counsel. Indeed we have had a further in depth meeting with the prosecution team at which we received the benefit of their thoughts on the case and the evidence to date. This is extremely useful for me and my team going forward as we continue to investigate Inga Maria's murder and we will now assess what is the best way to proceed.

"Our commitment to bringing Inga Maria's murderers to justice has been relentless.

"I would also make a direct appeal today to the family and friends of the murderer or murderers to come forward. If you are a family member who has information, or who even assisted the killer or killers in the aftermath of the incident, think hard about the impact of all this on Inga's family and step up and help bring an end to their plight.

In 2018, on the 30th anniversary of the murder, detectives said they believed a number of people may have been involved either directly or in the subsequent cover-up, and said they only need fractional pieces of evidence to bring the chief suspects to justice.

Police have a male genetic profile found at the murder scene.

A number of years ago, in one of the largest DNA screenings undertaken in the UK, 2,000 samples failed to produce a definitive match.

Ms Hauser had travelled through England and Scotland and, according to diary entries, intended to travel south to Dublin after her ferry docked at Larne, Co Antrim.

For reasons as yet unexplained, she ended up going in the opposite direction and was found dead two weeks later in a remote part of Ballypatrick Forest.