Dhaka, Bangladesh - In what observers have dubbed Bangladesh's "biggest-ever criminal case", 139 mutineers of a defunct paramilitary force were sent to gallows by the country's High Court (HC) on Monday.

Life sentences for another 146 people were also upheld by the court in the capital Dhaka. The mass convictions have been criticised by rights groups and the families, who say the trial was rife with procedural flaws and torture allegations.

At least 57 army officers and 17 civilians were killed during a mutiny in 2009 that the three-judge HC bench called "the most heinous, brutal and barbaric carnage" in Bangladesh's history.

For the family members of those killed, the verdict seems to have brought closure.

Syed Md Ismail Parvez, brother of Major Idris Iqbal who was killed on that day, told Al Jazeera that they "are happy" and want "the immediate execution of the perpetrators who had killed his brother and others.

"This will not bring my brother back. But at least it will let us know that justice is there to hold them accountable for what they did."

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But one of the main defence lawyers, Aminul Islam, called the verdict "too harsh" and based on "flimsy or no evidence". He said he would appeal against the HC judgement in the Supreme Court.

'Violation of human rights'

Relatives of many of the convicted paramilitary officials have raised questions on the impartiality of the trial, while rights groups have termed the whole trial process a "violation of human rights".

At least 47 suspects died while in police custody during the nine-year period of the trial.

Nargis Nasir, wife of one of the death row convicts - Nasir Uddin Khan, Deputy Assistant Director of the erstwhile BDR, said, "It's anything but a justice for us."

She said her husband was tortured and "forced to give confessional statement on the crime that he didn't commit".

"Since then, for the last nine years, our family is struggling to accept the fact that an innocent man was victimised for a crime of which he was no part."

Brad Adams, Asia director of HRW, said the convictions were obtained after "unfair trials".

"We interviewed many people who were badly tortured.… The courts and police should have investigated this but have failed to do so," he said.

"We have always called for the perpetrators to be held accountable, but in many cases there was no credible evidence against the specific individual charged.

"It is not acceptable to convict individuals for the crimes committed by others, or simply because they were in the wrong place at the wrong time."

A legal expert, who wished to remain anonymous, said that the trials probably were not of "international legal standards" and avoided considering "valid arguments" presented by the defence lawyers.

But Attorney General Mahbubey Alam told Al Jazeera that the HC bench delivered the verdict "after a thorough and careful investigation.

"Awarding death penalty even to an individual is not easy one. Here it was given to 139 people," the government lawyer said. "The High Court considered everything before giving that verdict."

Outside forces?

On February 25-26 in 2009, indignant members of the erstwhile Bangladesh Rifles (BDR), later renamed Border Guard Bangladesh (BGB), revolted against senior officers.

It initially appeared to be a few disgruntled Jawans (or soldiers) taking up arms against the deputed army officers in high positions of BDR, for better financial and working conditions, but later found to be a calculated massacre.

Among those killed was the then BDR chief Major General Shakil Ahmed and his wife. The remains of those massacred were dumped in sewers or buried in shallow graves.

Many theories have been doing the rounds about the nature of the mutiny and the real motives of the alleged perpetrators.

The most prominent of those theories suggested the involvement of "outside forces". The HC observations running in about thousand pages said: "There was a plot both from internal and external sides behind the BDR carnage, to uproot [Prime Minister] Sheikh Hasina-led government which came into power in 2008."

There is a need for digging deeper to unearth who was supposed to be the maximum beneficiary of such carnage. Mirza Fakhrul Islam Alamgir, opposition leader

Lt General (retired) Mainul Islam, who took over as the first Director General (DG) of the BGB right after the mutiny, however, told Al Jazeera he "had not found any evidence" of outside involvement.

According to him, the underlying reason behind the mutiny was the "prevailing discrimination between the army officials deputed in BDR and the BDR Jawans".

The question that befuddled many during that time, as well as now, is why the intelligence unit failed to get a sense of what might happen on the morning of February 25, 2009, even though there were many suspicious activities that should have raised red flags.

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The HC bench, in one of its recommendations, had called for investigating the failure of the intelligence unit in the purview of the carnage.

Critics and opposition leaders have called for an independent investigation into the incident.

Mirza Fakhrul Islam Alamgir, secretary general of the opposition Bangladesh Nationalist Party (BNP) said the killing of 57 top army officials in such a short span of time raises a lot of doubts.

"And it happened right after a new government came into power," he said. He said a probe needs to be conducted to find out whether it was "simply a ploy against a new government or against the whole nation.

"There is a need for digging deeper to unearth who was supposed to be the maximum beneficiary of such carnage."