Dhaka, Bangladesh - With the conviction of Bangladesh’s most prominent war crimes defendant on Monday, the case of a defence witness who disappeared for six months before turning up in an Indian prison has raised questions about the integrity of the controversial tribunal.

Shukhoranjan Bali - who is languishing in an Indian jail in Kolkata - said in a May statement given to a Bangladesh-based newspaper he was taken away by police when he stepped out of a car in front of the gates of the International Crimes Tribunal (ICT) in Dhaka in November last year.

Bali was on his way to give evidence on behalf of Delwar Hossain Sayedee, another defendant accused of committing acts of genocide and crimes against humanity during the country's 1971 independence war.

War crimes verdict raises fears of violence [EPA]

Bali's claim that he was abducted by Bangladeshi police supports allegations made in November 2012 by three of Sayedee's defence lawyers. However, the government and tribunal authorities have consistently denied that Bali had been abducted by law enforcement officers.

In February 2013, the tribunal sentenced Sayedee to death by hanging for two crimes committed during the war 42 years ago, one of which involved the killing of Bali's brother, Bisha.

Sayedee is one of more than a dozen men, mostly leaders of the political party Jamaat-e-Islami, either convicted or currently on trial for crimes committed during the bloody fight for independence.

Jamaat-e-Islami had opposed the break-up of Pakistan and the independence of Bangladesh. In the war that followed, its supporters are accused of setting up militias that fought alongside the Pakistani army.

The tribunal was set up in 2010 by the Awami League-led government to try those accused of crimes during the nine-month war that killed hundreds of thousands of people. Acts of mass murder, rape and arson were routinely carried out.

Jamaat-e-Islami - part of the opposition alliance headed by the Bangladesh Nationalist Party - says the war crimes tribunal is politically motivated to target its top leaders. But many Bangladeshis want it to bring justice for the crimes committed more than 40 years ago.

Ghulam Azam, 90, the head of Jamaat-e-Islami during the war, was convicted of war crimes on Monday and sentenced to 90 years in prison. There were concerns about possible violence erupting after Azam's conviction.

Taken away

The tribunal process has been controversial from its inception, and the story of the witness Bali’s disappearance has added to that.

According to the defence lawyers with him at the time, Bali was taken away by three plainclothes policemen who identified themselves as from the Detective Branch of the police and was put into a police vehicle that drove off.

No independent eyewitnesses came forward to corroborate this version of events - though two journalists working for a newspaper that supports Jamaat-e-Islami were present and confirmed the lawyers' story.

His wife and son also confirmed Bali had gone to Dhaka to give evidence at the tribunal.

The defence lawyers raised concerns with the tribunal's judges, who requested the head of the tribunal's prosecution and investigation agencies look into the matter. They returned to the court an hour later saying police officers on duty all denied that Bali had been detained by authorities.

For the tribunal, that was the end of the matter and proceedings resumed.

Defence attorney Abdur Razzaq told Al Jazeera that Bali was "a very important witness" in Sayedee's case.

Jamaat-e-Islami's Delwar Hossain Sayedee in 2011 [AFP]

"He has not been allowed to come to the court and depose and say 'my brother was killed, but not by Delwar Hossain Sayedee.'"

Sayedee's case is now under appeal at Bangladesh's Supreme Court. It is unclear if Bali's evidence would alter the guilty verdict, as other eyewitnesses put Sayedee at the scene of Bisha Bali's killing.

Bali's credibility may also be questioned since he previously was listed as a prosecution witness. An investigation officer has said Bali previously gave a strong statement implicating Sayedee in his brother's death.

"Armed Rajakers [collaborators] captured my brother Bisha Bali … Then according to the order of Delwar Hossain Sayedee, alias Delu, a Rajaker shot and killed my brother," the officer quoted Bali as saying in an unsigned statement, which wasn't used to convict Sayedee.

Bali also said in the statement issued from the Indian jail that he had been approached by one of Sayedee's sons at his home to testify on his father's behalf, and Bali later spent two weeks at Sayedee's house.

'Unacceptable drama'

Immediately after the alleged abduction in November 2012, tribunal prosecutors issued a statement saying the whole episode surrounding Bali was an "unacceptable drama" and "part of [Jamaat-e-Islami] trying to dismiss the tribunal and to release their leader unlawfully".

When the matter came up in a habeas corpus application at the High Court, the attorney general stated the story of Bali's alleged abduction "was absolutely ridiculous".

But in the statement obtained by Bangladesh's New Age newspaper from Bali at Kolkata's Dum Dum jail, he said he was abducted by Bangladeshi officers from outside the tribunal and taken to a police station.

They tortured me and asked me what I had been doing there ... They probably did not find my answers satisfactory, and I was beaten even more profusely. Shukhoranjan Bali

"They said that I will be killed and Sayedee sahib will be hanged," Bali said, adding he was not physically abused in Dhaka.

He said he remained in detention in the capital for six weeks before being blindfolded and "handed over" to India's Border Security Force (BSF) in December 2012.

Bali said he had been detained in various Indian jails for months, during which time he alleged physical abuse at the hands of the BSF.

"They tortured me and asked me what I had been doing there," Bali's statement said. "They probably did not find my answers satisfactory, and I was beaten even more profusely."

No independent confirmation exists to substantiate Bali's allegations.

Calls to a senior Border Security Force official in India rang unanswered. Requests for comment from India's Ministry of Home Affairs were not responded to.

Bangladesh's police, meanwhile, continue to deny involvement in Bali's alleged abduction.

Masuder Rahman, the media officer of the Dhaka Metropolitan Police, said he had "no information" about Bali's disappearance.

Call for UN intervention

New York-based Human Rights Watch said Bali's story raises questions about the integrity of the trial process.

"The apparent abduction of a witness in a trial at the ICT is a cause for serious concern about the conduct of the prosecution, judges and government," said Brad Adams, the group's Asia director. "Among many questions is who ordered the abduction, and how senior the officials involved were."

It is unclear why Bangladeshi police would have sent Bali to India. Human Rights Watch noted the " notorious " Border Security Force in the past has been known to kill Bangladeshis attempting to enter the country illegally.

"Those involved in his abduction may have assumed Bali would be killed by the Indian Border Security Force when he was pushed into India, or that he would permanently disappear," Adams said.

The rights group has called on the Indian government to allow the United Nations High Commissioner for Refugees to interview Bali.

"There is a real risk to Bali if he is returned to Bangladesh, as he could expose those involved in his abduction. Bali needs access to an independent lawyer and UNHCR so that he can make an informed decision about whether it is safe to return to Bangladesh."