The Khmer Rouge tribunal has closed an eight-year investigation into alleged Khmer Rouge naval commander Meas Muth, a spokeswoman for the court said yesterday.

A string of allegations have been made against Muth, including genocide and crimes against humanity, with a closing order - which will either indict him or dismiss his case - expected in six months’ time, court spokeswoman Hayat Abu-Saleh said.

The news comes despite Prime Minister Hun Sen repeatedly vowing that Muth’s case, known as Case 003, would not go ahead as it threatened Cambodia’s “stability”.

In his alleged roles as naval commander, secretary of a Revolutionary Army of Kampuchea division and a representative of the Military General Staff, Muth is alleged to have committed murder, extermination, enslavement, torture, forced labour, forced marriage and rape.

These crimes were allegedly committed at Phnom Penh’s notorious S-21 prison, islands claimed by Democratic Kampuchea and at a number of security centres and worksites.

International co-investigating judge Michael Bohlander announced yesterday that he considered the investigation now closed, but he also issued a separate decision reducing the scope of the investigation into Muth.

Details of that decision were not available as of press time.

Muth’s international defence lawyer Michael Karnavas said yesterday that this case was “far from over”. “We have a long journey ahead, and I do not expect smooth sailing for any involved in the process ahead,” he said in an email.

Muth’s national lawyer, Ang Udom, meanwhile, reiterated that his client had a right to an expeditious trial and said he had made repeated complaints that forced marriage should not be part of Muth’s case.

Prosecutor Nicholas Koumjian said yesterday’s step was one of several important milestones bringing the tribunal closer to completing its mandate and said the sexual and gender crimes should be considered because they can cause “tremendous long lasting damage to a society”.

The investigation into Muth has been long and controversial. It began in September 2009 and was initially “closed” in 2011 by national co-investigating judge You Bunleng and his then-international counterpart Siegfried Blunk. Blunk resigned as a judge that same year, citing government pressure, though some observers accused him of having attempted to quietly close controversial cases.

The scope of Muth’s case was expanded after the prosecution urged judges in October of 2014 to investigate additional crimes of forced marriage and rape in Kampong Som now Preah Sihanouk province.

The investigation into Muth’s fellow Case 003 suspect Sou Met was terminated with his death on June 2, 2015.

A draft US bill in July last year stipulated the US would only provide further funds to the Khmer Rouge tribunal if it pushed ahead with Case 003, as Meas Muth was allegedly implicated in the 1975 capture of the SS Mayaguez, an incident that ultimately led to the deaths of 41 Americans.

The closure of the investigation into Muth comes a month after the investigation into Case 004 suspect Ao An was concluded and severed into Case 004/02, and two months after the tribunal upheld life sentences for former Brother Number Two Nuon Chea and head of state Khieu Samphan.