Abu Sayyaf, an Islamic militant group from the southern Philippines notorious for abducting foreigners, beheaded a Canadian hostage on Monday.
Canadian Prime Minister Justin Trudeau said he was “outraged” by the killing, and authorities were trying to free another Canadian still being held along with a Norwegian man and a Filipina.
Here are five facts about Abu Sayyaf:
The group is a radical offshoot of a Muslim separatist insurgency that has claimed more than 100,000 lives in the south of the mainly Catholic Philippines since the 1970s.
It was established in the 1990s with funds from a relative of former al Qaeda leader Osama bin Laden.
Abu Sayyaf’s strongholds are the Muslim-populated islands of Jolo and Basilan in the far south of the Philippines, about 1,000 kilometres from Manila.
Sallying forth in fast boats from the islands, the Abu Sayyaf snatches local and foreign victims, demanding ransom payments for their freedom.
Hostages, many of them Western tourists but also Christian missionaries and locals, are then hidden among sympathetic Muslim communities on Jolo and Basilan.
Victims are often murdered if ransoms are not paid -- the Abu Sayyaf beheaded an American man in 2002, as well as a Malaysian last year.
The United States lists the Abu Sayyaf as a “foreign terrorist organisation”.
From 2002-2014, the US deployed Special Forces advisers to train and provide intelligence to Filipino troops, which led to the killing or arrest of many Abu Sayyaf leaders.
US assistance was scaled back after the Pentagon concluded the group, originally with about 1,000 fighters, had lost the ability to launch international attacks.
Since then, Abu Sayyaf has launched a series of raids on foreigners and locals, as well as engaged in battles with Filipino troops that have killed dozens from both sides.
A German couple abducted off their yacht in 2014 was released after six months, with a ransom of more than $5 million believed to have been paid.
In September last year, gunmen seized two Canadians, a Norwegian and a Filipina from a Philippine resort island. When an April 25 deadline for a ransom of three million pesos ($6.3 million) passed, the severed head of Canadian John Ridsdel was dumped in a Jolo street.
Fourteen Indonesians and four Malaysians have been abducted from boats in waters near the southern Philippines over the past month, an unusual expansion of operations against sailors and away from targets along the coast.
In recent years, several Abu Sayyaf units, along with other small armed groups in the south, have publicly pledged allegiance to the Islamic State group that holds vast swathes of Iraq and Syria.
IS, known for its black flag and brutal interpretation of Islamic law, has acknowledged them and cited the Abu Sayyaf in its communiques and news reports.
Philippine authorities and security analysts say the pledges are just ploys to draw attention and potential funding from IS. They say the Abu Sayyaf is less interested in Islamic ideology than in getting rich from kidnappings.