ISIS militants released a grisly new video Sunday morning showing the mass execution of Syrian soldiers and the purported severed head of American aid worker Peter Kassig. Kassig—a former Army Ranger—was kidnapped while delivering medical supplies in northern Syria last year.

Unlike previous beheading videos released by ISIS, the clip does not contain footage of their captive's execution, showing only a bloodied head at a masked figure's feet.

Kassig's family released a statement on Sunday saying they are waiting for official confirmation of their son's death. According to the BBC, authorities are still working to authenticate the video.