Canadian Prime Minister Justin Trudeau has raised concerns over the death of a Canadian mining executive, John Ridsdel, on Monday and called it an “act of cold-blooded murder.”

Ridsdel, 68, was kidnapped from a tourist resort by the ISIS militants in September 2015 during his vacation in the Philippines. He was captured along with three more people and has been held captive for months by al-Qaeda funded Abu Sayyaf militants in the Philippines.

According to the BBC, the Philippine army confirmed the recovery of a severed head from a Philippine island on Monday five hours after the expiry of the deadline for the Abu Sayyaf ransom. The militants warned the authorities earlier that if the ransom is not offered to them within the specified time, they would kill one of the four hostages. Though the army has not confirmed yet that the head belonged to Ridsdel, the prime minister confirmed the death of the ex-mining executive and called the killing a “cold-blooded murder.”

“Canada condemns without reservation the brutality of the hostage-takers and this unnecessary death. This was an act of cold-blooded murder and responsibility rests squarely with the terrorist group who took him hostage,” Trudeau told Reuters. “The government of Canada is committed to working with the government of the Philippines and international partners to pursue those responsible for this heinous act.”

Ridsdel was kidnapped along with another Canadian, Robert Hall, his Filipina girlfriend Marites Flor, and Norwegian Kjartan Sekkingstad. The Canadian prime minister seemed silent when asked whether the government negotiated with the militants on paying a ransom or releasing the captives. He did not even respond to questions relating to the release of another Canadian hostage, Robert Hall.

Ridsdel’s friend, Bob Rae, told CBC News that it was hard to remain behind the scenes for the last few months and to try to find solutions to get him back. He called the attempt “very painful.” “Obviously, there was talk of money involved, but not by the government of Canada or by the government of Norway, but certainly by the families attempting to do what they could to free the four,” Rae said.