(CNN) — John Ridsdel, a Canadian held hostage by Islamist militants in the Philippines, “has been killed at the hands of his captors,” Canadian Prime Minister Justin Trudeau said in a statement Monday.

“This was an act of cold-blooded murder and responsibility rests squarely with the terrorist group who took him hostage,” Trudeau said, emphasizing that Canada condemns the “brutality” of this “unnecessary death.”

Ridsdel had been held hostage with three others since September of last year. Last month Islamist militant group Abu Sayyaf released a video that appeared to show Ridsdel and the other captives pleading for their lives, as armed masked men stood behind them.

One of the masked men in the video had threatened to “do something terrible against these captives” if the captors’ demands — which included ransom — were not met.

On Monday, Trudeau expressed his “deepest condolences” to the family and friends of Ridsdel.

Trudeau said Canada would not comment or release any information that could compromise the other hostages’ safety or ongoing efforts to release them.

Developing story – more to come