Bangladeshi war criminal Ghulam Azam, who was sentenced last year to 90 years in prison for masterminding atrocities during the country's 1971 independence war, died late Thursday aged 91.
Azam was the wartime head of Jamaat-e-Islami -- the country's largest Islamist party, later turning into its spiritual leader and a key player in the country's politics.
He died of a heart attack while in custody at a hospital in the Bangladeshi capital Dhaka, director of the Bangabandhu Sheikh Mujib Medical University hospital Abdul Majid Bhuiyan told reporters.
"He died of cardiac arrest at 10.10 pm today," the director said.
Azam's son, Abdullahel Azmi, told AFP earlier on Thursday that his condition had deteriorated at the hospital, prompting the authorities to put him on life support.
"He was suffering from old age complications. He also did not get adequate care in the hospital," his lawyer, Tajul Islam, said.
Azam was found guilty of five charges of war crimes, including crimes against humanity, last July by a special war court crimes court set by the country's secular government.
Prosecutors had sought the death penalty for Azam, comparing him to Nazi leader Adolf Hitler.
They described him as a "lighthouse" who guided all war criminals and the "architect" of militias which committed many atrocities during the war against Pakistan in 1971.
When India intervened at the end of the nine-month war, 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 their bodies were found a few days after the war at a marsh outside the capital, blindfolded and with their hands tied behind their backs.