Ghulam Azam, sentenced to 90 years in jail on Monday for crimes committed during Bangladesh's 1971 liberation war, was the Islamist mastermind behind the atrocities who was compared with Hitler by prosecutors.
The one-time political science professor and author of over 100 books dabbled with left-wing politics before joining the Jamaat-e-Islami party in the 1950s. He led the party when Bangladesh — known as East Pakistan after the partition of British India in 1947 — went to war against Pakistan.
Under his leadership, the party opposed secession from what was then West Pakistan, which lay 2,000 kilometers (1,235 miles) away, with only Islam, the faith of the majority, binding the two peoples together.
Prosecutors said Azam, now 90, played a "pivotal role" in creating pro-Pakistani militias such as Rajakar, Al-Badr, Al-Shams and Peace Committee, blamed for many of the atrocities during the war, which the government says killed three million people.
Prosecutors have compared him to Nazi leader Adolf Hitler. They described him as a "lighthouse" guiding war criminals and the Pakistani military to commit many of the 1971 atrocities.
"His role in the 1971 war was like Hitler's in the Second World War," state prosecutor Sultan Mahmud said.
"He was not commander in chief like Hitler, but he was the defacto leader of the pro-Pakistani auxiliary forces (militias) and the leader of the notorious Peace Committee and the Jamaat-e-Islami, which carried out most of the war atrocities," he said.
When India intervened at the end of the nine-month war and it became clear Pakistan was losing, the militias killed dozens of professors, playwrights, filmmakers, doctors and journalists.
Azam was described as the "mastermind" of the massacres of the intellectuals, many of whose bodies were found a few days after the war in a marsh outside the capital, their hands tied behind their backs and blindfolded.
"The aim was to cripple the country intellectually. Without his consent it could not have happened," said Mahmud.
Azam's lawyer Tajul Islam said the charges were based on newspaper reports of speeches Azam gave during the war, which led to the creation of Bangladesh. "They were false and baseless," he said.
After the war, Azam fled to Pakistan where he allegedly formed the East Pakistan Restoration Committee, portraying the liberation war as a conspiracy by India.
He left Pakistan for London in 1973 where he edited a Bengali newspaper and continued to campaign against recognizing Bangladesh's independence.
After independence, Bangladesh canceled Azam's citizenship and banned Jamaat and other faith-based parties when it adopted a secular constitution. Thousands were arrested for collaborating with the Pakistani regime.
Azam returned to Bangladesh bearing a Pakistani passport in 1978, three years after the nation's founding leader Sheikh Mujibur Rahman was assassinated and a junta took over, allowing Islamic parties to operate openly again.
Under his stewardship, Jamaat staged a revival by setting up a new student wing that has become a formidable force with thousands of loyal cadres.
His political rehabilitation was complete in 1993 when the Supreme Court returned his citizenship. After the judgment, he apologized for his past activities but fell short of giving a full apology for his war time role.
Although his party has never won more than five percent of votes, he played a kingmaker's role after democracy was restored in 1990, allowing the Bangladesh Nationalist Party to come to power.
In 1996, he changed tack and allied with Sheikh Hasina, the current premier and the daughter of independence hero Sheikh Mujib, helping force her bitter rival Khaleda Zia of the BNP to resign and accept a caretaker administration.
Before he quit politics in 2000, he steered Jamaat back to an alliance with Zia's centre-right party ahead of the 2001 polls. Zia won by a landslide and formed a cabinet which included two ministers from Jamaat.
Hasina did not forget the humiliating loss. She stormed back to power in 2009 on the back of growing youth-led anti-Islamist sentiment and this time she vowed to try all those who committed war crimes during the 1971 war.
In January 2012 an octogenarian and wheel-chair bound Azam was arrested at his home in the capital on five war crime charges including conspiracy, planning, incitement, complicity and murder.