Deputy police commissioner Nahidul Islam said. The attackers used sharp weapons and fled the scene immediately.
The Islamic State group claimed responsibility for the attack, accusing Siddique of encouraging atheism, according to the SITE Intelligence Group, which monitors jihadi websites.
IS has claimed responsibility for other attacks in Bangladesh, but the government has dismissed those claims, saying that ISIS has no presence in Bangladesh.
At least three other professors at Rajshahi University have been killed in recent years, allegedly by Islamist groups.
“So far as we know, he did not have any known enemies and we never found him worried,” the brother said. “We don’t know why it happened to him.”Following Saturday’s attack, hundreds of students and lecturers marched on Rajshahi University’s campus and blocked a highway, demanding justice for the professor's death.
Amnesty’s South Asia director, Champa Patel, in a statement said:
“The vicious killing … is inexcusable and those responsible must be held to account,” “This attack sadly fits the gruesome pattern established by Islamist extremist groups in Bangladesh who are targeting secular activists and writers.”
“The authorities must do more to put an end to these killings. Not a single person has been brought to justice for the attacks over the past year,” Patel said.