Suspected Islamist radicals hacked Mannan and his theatre activist friend Mahbub Rabbi Tonoy at Xulhaz’s apartment in Dhaka’s Kalabagan on Monday.
Witnesses said the assailants shouted ‘Allahu Akbar’ while fleeing the scene.
Xulhaz had spoken several times about the hostility he had faced while working for the gay rights, which are not widely accepted even in the West.
None of the major religions accepts same gender relationship.
The gays have achieved rights in around two dozens of countries after a long and difficult struggle. Only recently have some started speaking for them in Bangladesh.
The country’s only LGBT magazine, ‘Roopbaan’, was launched in 2014. Thirty-five years old Xulhaz was on its panel of editors.
“Roopban doesn’t actually want to present the issues of homosexuality, but the right to love of those who believe in same gender love,” said Xulhaz, a programme officer at USAID.
He spoke about the challenges he had faced in publishing the magazine.
‘Roopban’ initiated ‘Rangdhanu Jatra’ (rainbow parade) on the occasion of Bangla New Year on Apr 14 this year like last year, but police foiled the march.
Xulhaz cited a Bangla saying that ‘A mother doesn’t give milk if the baby doesn’t cry’, and said he ‘strongly believed’ the LGBT community in Bangladesh should step forward to establish their rights.
“Many would speak about its negative impacts, but if we can’t come out and raise our voice in support of our demands, then how shall we hold society and the State responsible for not accepting us,” he asked.
Xulhaz studied international relations at the Dhaka University and joined the US embassy in 2007 before talking up what proved to his last assignment at the USAID.
He lived in the Kalabagan flat with his 90-year-old mother Sakhina Khatun.
His father Abdul Mannan is a retired public servant hailing from Chandpur’s Shahrasti.
Xulhaz was the youngest among three brothers and a sister. His elder brother Minhaz Mannan Emon is a former vice president of Dhaka Stock Exchange. The other brother lives in the US.
His slain friend Tonoy was with theatre group Lok Natyadal. According to the profile on his Twitter handle, he worked as a drama trainer of children in an organisation going by the name of PTA.
Police did not immediately say who carried out the attack. But the killings of Xulhaz and Tonoy bore striking similarities to those of secular bloggers and online activists, claimed by radical Islamist groups, in the recent past.