An Islamic State-affiliated group in the Philippines posted a video on Monday purporting to show the beheading of a 71-year-old German hostage after a deadline for his ransom had expired, a monitoring group reported.

The SITE Intelligence Group said the video was posted by the Abu Sayyaf group on its Telegram social media account and follows Sunday’s deadline for about $600,000 in ransom.

The authenticity of the video could not be confirmed independently, but a German government spokesman called the slaying a “sad certainty.” Abu Sayyaf has carried out similar beheadings of captives in the past, and the latest video brought swift condemnation from authorities in the Philippines.

“We grieve as we strongly condemn the barbaric beheading of yet another kidnap victim,” said Jesus Dureza, an adviser to Philippine President Rodrigo Duterte.