The International Crimes Tribunal sentenced Islam to death after finding him guilty of charges like genocides, murders, tortures and rapes.
"He shall be hanged by neck until he is dead," pronounced chairman of the three-member panel of judges Justice Enayetur Rahim while delivering a 158-page verdict after Islam appeared on the dock.
He said the convict deserved no punishment other than death penalty as five of the six charges against Islam were proved beyond doubt while in subsequent years after the independence he never showed any gesture of remorse for his acts in 1971.
Under the law, Islam, however, could challenge the verdict in the Supreme Court while he is the last of the top Jamaat leaders who were exposed to justice for committing crimes against humanity siding with the Pakistani troops in 1971.
Islam, 61, was charged on six counts of atrocities and in one of the major proven charges he was accused of is leading the massacre of 1,225 people in Rangpur. He was also found guilty of abducting and murdering a CarmichaelCollege professor and his wife.
Tight security vigil was enforced as a microbus carried Islam, attired in a cream colour coat, to the tribunal at the Supreme Court complex in the central part of the capital from Dhaka central jail.
Senior police officials including Dhaka's police commissioner visited the court complex to oversee the security arrangements with witnesses saying extra numbers of CCTV cameras were installed in different parts of the compound to enforce a close vigil on activities of the visitors.
Islam was arrested in August 2012 and was indicted on November 12 last year while the prosecution lawyers said they were satisfied with the judgment as they successfully proved the charges with adequate evidence.
"But we are not at all satisfied with the verdict. It was based on fictitious testimonies of witnesses, we will challenge the verdict in the Supreme Court," defence counsel Tazul Islam told reporters.
This was the 15th judgment delivered so far by the two special tribunals since Bangladesh initiated the belated trial of the leading Bengali-speaking collaborators of Pakistani troops in 2010 in line with ruling Awami League's election pledges.
In the previous 14 cases the tribunals tried 15 people and handed down death penalty to 12 people while three of them were tried in absentia as they fled the country to evade justice.
But in the appeal process against the verdicts, the Supreme Court enhanced the life imprisonment of one of the convicts – Jamaat leader Abdul Quader Mollah -- to death penalty, finding the tribunal verdict too lenient.
In another case, the apex court reduced the death sentence of another Jamaat stalwart Delwar Hossain Sayeedi ordering him to be imprisoned until his death.
The apex court also commuted the capital punishment of another convict Delwar Hossain Sayeedi to life imprisonment.
Mollah, also an assistant secretary general of Jamaat was subsequently executed and so far he was the lone convict to walk to gallows.
The apex court last month also cleared ways for execution of another assistant secretary general of Jamaat – Mohammad Quamaruzzaman – rejecting his appeal but accepted his prayers for a review of the judgment by the Supreme Court itself, which is now pending for hearing.
The rest of the tribunal judgments now also await hearing in the apex court for review under appeal prayers by the convicts.
Most of the convicts were stalwarts of Jamaat which had supported the then Pakistani junta in 1971 forming militia groups like Razakar and more notorious Gestapo like Al-Badr secret killing forces.
They included Jamaat's then East Pakistan wing chief Ghulam Azam, incumbent Jamaat chief Motiur Rahman Nizami and secretary general Ali Ahsan Mohammad Mujahid.
Of the rests, two were senior leaders of Bangladesh Nationalist Party and served as ministers while the party was in power.
Only one of the convicts is an expelled local leader of ruling Awami League.
Officially, three million people were killed in the war by the Pakistani army and their Bengali-speaking collaborators during the 1971 Liberation War.
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