Genocide is always a difficult crime for courts to deal with, and all the more so when it happened 42 years ago.
But Bangladesh is really making a mess of it - largely because most of the old men on trial are leading members of a political party that is part of the country's official opposition.
''It is undeniable that a massive genocide took place in the then East Pakistan,'' Justice Anwarul Haque said last week as he imposed a death sentence on Ali Ahsan Mohammad Mujahid, the Secretary-general of the Jamaat-e-Islami party.
''This massacre can only be compared to the slaughter by Nazis under the leadership of Adolf Hitler.''
That is an exaggeration, but not a very big one. The official Bangladeshi estimate is that 3 million people were killed, and 200,000 women were raped, by the Pakistani army and its local collaborators during the independence war of 1971.
For 15 years after the partition of India in 1947, it was just the eastern wing of Pakistan, a country in two parts with a lot of Indian territory between them. But it was always controlled by the western half (today's Pakistan), and when it attempted to break away in 1971 the Pakistan army tried to drown the independence movement in blood.
It was aided by local paramilitary groups, made up mostly of pious Muslims who believed that Pakistan must be preserved as the single home for all the subcontinent's Muslims. Initially, they targeted secular intellectuals and the Hindu minority for murder, but in the end they were slaughtering whole villages that supported the nationalist cause. The killing lasted for nine months.
Eventually, the Indian army intervened and the Pakistani forces were forced to surrender. But the Pakistani soldiers were all sent home, and the leaders of the local paramilitary forces that fought alongside them fled abroad. And then, after some years in exile, the leaders of the genocide came home again and went into politics.
They came home because a military coup in 1975 virtually exterminated the family of Mujibur Rahman, the secular politician who led the country to independence. The generals who wound up in power tried to win popular support by pushing an Islamic agenda, which left the returned exiles free to found the Jamaat-e-Islami Party. By the 1990s, when democracy returned, they were even serving as junior partners in governing coalitions.
Their senior coalition partner was the Bangladesh Nationalist Party, created by one of the generals and still led by his widow, Khaleda Zia. The other main party, the Awami League, is led by Sheikh Hasina, the daughter of the martyred ''father of the nation'', Mujibur Rahman. Their bitter rivalry has dominated Bangladeshi politics for the past 20 years.
Sheikh Hasina promised to put the perpetrators of the genocide on trial in her election platform in 2008. She won by a landslide, and the trials began in 2010.
There was strong international support for her decision at first, but the conduct of the trials has left much to be desired. Most of the accused were certainly implicated in the killing, but the BNP has quite rightly accused the Government of politicising the trials.
The Jamaat-e-Islami has portrayed the trials as an attack on Islam, and when the first death sentence was handed down in February there were violent nationwide protests by the Jamaat-e-Islami's Youth League, leaving about 150 people dead.
When the first life sentence was given out a few days later, hundreds of thousands of other young people demonstrated to demand the death penalty for all of those convicted.
They were driven by the fear if the BNP wins the next election (due by January), then it will grant amnesties to all the surviving Jamaat leaders to preserve its electoral alliance with the Islamist party. The Awami League has responded to their demand by passing a new law shortening the time allowed for appeals, so they can be hanged before the next election. Lynch law.
There is a way out of this, and it could end the 20-year stalemate in Bangladeshi politics. In a poll before the last election, four out of five young Bangladeshis said they wanted to see the perpetrators of the genocide brought to trial: the crimes have not been forgotten. So give them what they want, but don't kill anybody.
The Awami League said that it was setting out to exorcise ''historical ghosts'', and it can do so without hanging old men. Nor does the BNP need to preserve its alliance with Jamaat-e-Islami: the party only got 3% of the vote in the last election.
It would take more statesmanship than either party has shown in the past, but it would open the way to a better future for the country.
Gwynne Dyer is an independent London journalist.
