British police said Monday they were investigating a video linked to a man armed with a crossbow who was arrested at Windsor Castle on Christmas Day.

The video, obtained by The Sun newspaper, showed a masked person in a dark hoodie holding a crossbow and addressing the camera with a distorted voice, saying they wanted to “assassinate” Queen Elizabeth.

The Sun said the video was sent from the suspect’s Snapchat account shortly before he was arrested.

Police said they arrested a 19-year-old man within the grounds of Windsor Castle after a security breach took place on Christmas morning. Officers found