A small group of Islamist militants in the Philippines, known as Abu Sayyaf, has beheaded a second Canadian hostage in two months, authorities said Tuesday.

“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,” Herminio Coloma, a representative for the Philippines President Benigno Aquino, said in a statement, according to AFP. A head believed to belong to Hall,  58, was found Monday on an island near an Abu Sayyaf outpost.

In April, the same group decapitated Canadian John Ridsdel, a 68-year-old businessman. Gunmen had kidnapped Ridsdel and Hall, along with Hall’s Filipina partner Marites Flor and a resort manager from Norway named Kjartan Sekkingstad, from the island of Samal in September.

Justin Trudeau, the Canadian prime minister, condemned the Islamist terrorists in a statement Monday night.  “The vicious and brutal actions of the hostage-takers have led to a needless death,” Trudeau said in a statement posted on Facebook. “Canada holds the terrorist group who took him hostage fully responsible for this cold-blooded and senseless murder.”

Abu Sayyaf has a decades-long history of taking hostages and demanding ransoms, which both the Canadian and Philippine governments oppose paying. AFP reports that Abu Sayyaf murdered Hall when a $6.5 million ransom demand was not met.

The Philippine military has raided Abu Sayyaf strongholds in the past, and the Canadian prime minister said his government would support further action. “We are more committed than ever to working with the Government of the Philippines and international partners to pursue those responsible for these heinous acts and bring them to justice,” Trudeau said, “however long it takes.”

The BBC reports that some factions of Abu Sayyaf, rebelling against the majority-Catholic nation, have pledged allegiance to the Islamic State. As of Tuesday, the fates of Flor and Sekkingstad, and that of a Dutch birdwatcher abducted in 2012, remained unknown.