Prosecution witness Mustafa Howlader died Dec 10 after being attacked in his home. Howlader appeared in the case against Delwar Hossain Sayedee, a leading figure in the Jamaat-e-Islaami party.
"War crimes trials have become flashpoints for political tension and violence in Bangladesh," said Brad Adams, Asia director at Human Rights Watch.
"The killing of a prosecution witness will frighten past and future war crimes trial witnesses, and some may choose not to testify."
Howlader had been receiving death threats from unknown callers. As a result, police were assigned to protect him.
However, according to his son, police officers expected the family to feed them, which cost them more than Howlader made in a day, Human Rights Watch said.
After this, the police provided Howlader an escort on his way back from work but did not stay to guard the house.
Howlader's family said that the attacker had first attempted to "chop" Howlader's wife, seriously injuring her in the arm, before proceeding to attack Howlader with a machete.
Six people have been arrested. Jamaat has denied any involvement in the attack.
--IANS (Posted on 24-12-2013)