LONDON -- Prayers were being offered in churches and mosques for Alan Henning, a British aid worker murdered by Islamic State militants, as another Briton was reunited with his family after being freed by captors in Libya.

A church in Henning's home town of Eccles, northwest England, was holding a multi-faith service of "reflection and solidarity" in his memory Sunday.

Muslim leaders also urged worshippers to pray for the 47-year-old taxi driver, captured while delivering aid to Syria, as they gathered this weekend to celebrate the Eid al-Adha holiday.

A video purportedly showing Henning's beheading was released by militants Friday.

Imam Asim Hussain of the Manchester Central Mosque said Henning's killers did not represent the true face of Islam.

"They are not Islamic in any way, nor are they a state," he told the BBC. "Neither do we as Muslims ... consider them to be Muslims."

Prime Minister David Cameron vowed to use "all the assets we have" to hunt down and punish Henning's killers. British fighter jets are involved in U.S.-led attacks on Islamic State militants in Iraq -- but not in Syria, where the militants are thought to be based.

In the wake of Henning's death, former senior military chiefs have called for Britain to expand its military operation to Syria.

Cameron has said no British ground forces will take part in the conflict against the Islamic State group, but he could authorize a special forces mission against the captors of Henning and other Western hostages.

The militant video Friday was the fourth released by the Islamic State group. Previous victims were American reporter James Foley, American-Israeli journalist Steven Sotloff and British aid worker David Haines. It ended with a militant threatening a 26-year-old American hostage, Peter Kassig.

Another British hostage crisis ended in relief rather than tragedy.

Late Saturday, the British government announced the release of David Bolam, a teacher at the Benghazi European School in eastern Libya. He was captured in May by a group calling itself the Army of Islam.

The BBC reported that his release was secured by local politicians after a ransom was paid.

The Foreign Office said the British government was not involved in the negotiations. British officials have strongly criticized countries that pay ransoms to militant groups.