Under a grey spring sky, a young man wearing a blue knitted hat and carrying an Adidas backpack walks along a park path before two broad security operatives spring from a van, forcing him onto the pavement.

"What is your name?" a voice asks in English as a gloved hand tilts his face towards the camera.

"David Adrian Kercso," he answers promptly, confirming his background when asked where he is from: " Romania . Romania."

Published by state media and released by Russia 's FSB security service, the footage claims to show the arrest of Kercso, a 23-year-old Romanian citizen who grew up in England. He was sentenced earlier this year to 15 years in prison for spying for Ukraine .

Although not all evidence in Kercso’s case can be verified, an examination of the clip and court records reveals the video is not what it purports to be.…