No one has been arrested or claimed responsibility for either attack. JI on 17 February condemned the murder of Haidar and said it was not involved.
"We urge the authorities to carry out a thorough, independent and impartial investigation into these attacks, otherwise violence could continue with impunity," Faiz said.
Equally at risk are journalists and bloggers critical of the ICT.
Amnesty International has received disturbing reports that some individuals criticising the tribunal's proceedings have been threatened and may be at risk of retaliatory violence.
The ICT was set up in 2010 to try people suspected of crimes under international law, including genocide, war crimes and crimes against humanity, committed during the country's 1971 war of independence.
The Shahbag neighbourhood of Dhaka has witnessed mass protests calling for Molla to be sentenced to death since February 5. Amnesty International opposes the death penalty in all circumstances.
Meanwhile, JI has been holding rallies throughout the country and calling for daylong strikes, demanding the release of their leaders who are on trial at the ICT.