“We believe that the evidence is compelling that these crimes were not the acts of rogue individuals acting on their own accord, but rather that they were conducted in an organised fashion,” said Williamson, who was appointed to lead the Special Investigative Task Force (Sitf) in October 2011.

Sitf was set up to probe allegations of KLA crimes following a 2011 report by Dick Marty, an investigator at the human rights watchdog, the Council of Europe. Similar allegations were made in a separate report by Human Rights Watch, an NGO.

The Kosovo Albanian military outfit disbanded in 1999 but is implicated in the death and disappearance of around eight hundred people after the war’s official end in June of the same year.

Murder, abductions, enforced disappearances, illegal detention in camps in Kosovo and Albania, sexual violence, and violence against political opponents to obtain power and personal wealth is among the list of crimes linked to high-ranking people inside the guerrilla outfit.

Other serious allegations involve a handful of organ trafficking cases.

Williamson said around ten people were abducted so that their organs could be removed and sold on the black market.

“There are compelling indications that this practice did occur on a very limited scale and that small number of individuals were killed for the purpose of extracting and trafficking their organs,” he said.

A “climate of intimidation” made it difficult for the team of investigators to collect hard evidence so organ trafficking is not including in the indictment.

“We have faced challenges due to a climate of intimidation that seeks to undermine any investigations of individuals associated with the former Kosovo Liberation Army – the KLA,” he said.

Williamson would not go into detail on the types of threats experienced but described the intimidation of witnesses in Kosovo as one the greatest threats to its rule of law.

“As long as a few people continue to thwart the investigations into their own criminality, the people of Kosovo as a whole pay the price,” he said.

Many former KLA officials went onto leadership positions after Kosovo declared its independence in 2008.

Hashim Thaci, Kosovo’s caretaker prime minister and former leader of the KLA, was cited in Dick Marty’s report as being involved in the criminal activities.

Secret Nato documents leaked to the Guardian in 2011 say the former guerrilla leader was one of “the biggest fish” in organised crime.

Williamson, for his part, would not name anyone in the upcoming indictment or confirm if they are active in Kosovo politics until a court has been created to charge them.

“This is an unusual – in fact, an unprecedented – situation in international justice where a special prosecutor’s office has been set up with full investigative authorities and with a mandate to issue indictments, but where no viable court exists in which those indictments can be filed,” he said.

It is unclear when the court will be officially established and where it will be based.

The court would be staffed entirely by international experts, prosecutors, legal officers, investigators, analysts and international judges.

Williamson said early next year would be a “best case scenario” for it to be up and running.