Philippine authorities on Tuesday confirmed that Muslim extremist guerrillas had beheaded a second Canadian hostage, as they defended their inability to save him despite months of pursuit. The Abu Sayyaf, a small group of militants based on remote and mountainous southern islands that specializes in kidnappings-for-ransom, killed Robert Hall after its demands for 300 million pesos ($6.5 million) by Monday were not met. "We strongly condemn the brutal and senseless murder of Mr. Robert Hall, a Canadian national, after being held captive by the Abu Sayyaf group in Sulu for the past nine months," presidential spokesman Herminio Coloma said in a statement. A military statement confirmed that a severed head, believed to be Hall's, was found near a cathedral on Jolo, the main island in the Sulu archipelago that is one of the Abu Sayyaf's strongholds. In announcing on Monday night that he feared Hall had been killed, Canadian Prime Minister Justin Trudeau expressed outrage while maintaining that ransoms should not be paid. "The vicious and brutal actions of the hostage-takers have led to a needless death. Canada holds the terrorist group who took him hostage fully responsible for this cold-blooded and senseless murder," Trudeau said. Hall, a retiree, was among four people abducted last September from aboard yachts at a tourist resort on Samal island, about 500 km to the west of Sulu. Another Canadian kidnapped with him, John Ridsdel, was beheaded in April after a similar ransom demand of 300 million pesos was not paid. The fates of the two other people abducted at the Samal resort — Hall's Filipina girlfriend Marites Flor and Norwegian resort manager Kjartan Sekkingstad — were unknown on Tuesday, but the Abu Sayyaf had also previously demanded ransoms for them. Muslim rebels have been waging a separatist insurgency in the south of the mainly Catholic Philippines since the 1970s, and the conflict has claimed more than 100,000 lives. The Abu Sayyaf is a loose network of a few hundred militants that broke away from the main rebel groups in the early 1990s, evolving into a radical offshoot focused heavily on kidnapping Filipinos and foreigners in largely successful bids to extort money. Its leaders have in recent years declared allegiance to the Daesh group that holds territory in Iraq and Syria, but security analysts believe it is chiefly interested in ransom rather than religious war. While having only a relatively small number of armed followers, it has proved extremely resilient against repeated military offensives. From 2002-2014, the US deployed special forces in the southern Philippines to train Filipino troops to combat the Abu Sayyaf, a move which led to the killing or arrest of many Abu Sayyaf leaders. But the Abu Sayyaf went on a sustained kidnapping spree after the Americans left. It has abducted 44 Filipinos and foreigners since the beginning of last year, according to Pacific Strategies and Assessments (PSA), a security intelligence group. Most have been released after ransoms were paid, although it is still believed to be holding at least eight people including a Dutch bird watcher abducted in 2012. After the beheading of Ridsdel, Philippine President Benigno Aquino vowed to "neutralize" the Abu Sayyaf and ordered a fresh offensive that PSA said involved more than 4,000 troops. Major Filemon Tan, spokesman for military forces in the south, on Tuesday defended their performance and highlighted difficulties — such as support for the group from the impoverished Muslim residents on Jolo island. "They have relatives in the community. They are the ones that give them a warning when there are soldiers in the area," Tan told radio station DZMM. He also said the island's forested, hilly terrain, a broad coastline that allows for swift movement by boat and the kidnappers' tactic of breaking up into smaller groups, were all hindering pursuit.