The family of missing man Allan Bryant only learned from a tip-off from a police officer that a troll who taunted them online will be on a BBC documentary tonight.
They face the anguish of seeing Stewart McInroy on the BBC Three programme about internet bullies and abusers.
Allan Bryant Sr and his family had no input to the show and criticised the BBC for failing to even inform him it would be screened.
McInroy was jailed for 10 months in August 2014 for sending them a series of sick messages claiming he had taken Allan Jr hostage and tortured and killed him.
Mr Bryant’s initial fury that McInroy was to be given publicity has subsided but he said he would have liked to have been informed by the BBC.
He said: “It would have been nice to have had a heads-up rather than getting tipped off by a policeman.
“When I first heard, I was absolutely raging. This is something we have put behind us.”
However, he added: “It can only be a good thing if it keeps Allan in the public eye and it is going to expose him (McInroy) as a troll for what he has done to me and my family.
“When he did this it caused us real concern, we wondered if this guy was real. It caused us a lot of heartache and pain. He is a very, very sick individual.”
Allan Jr was 23 when he disappeared after a night out in Glenrothes more than two years ago.
He had been at the Styx nightclub and CCTV footage showed him leaving in the early hours of the morning.
However, he never returned to the family home in the town.
Troll Hunters looks at the rise of online abuse in Britain, exposing the trolls responsible and highlighting the impact on victims.
McInroy also waged a campaign of abuse against his former girlfriend, threatening to hurt a dog and a small child and burn her house down.
A spokesman for the BBC said: “This programme examines the nature of trolling and its impact on victims. A short scene contains our presenter, who herself has been a victim of trolls, confronting and challenging Stewart McInroy about his trolling activity.
“He is questioned about if he understands the impact on the victims, however the programme does not include any personal details about the case in question.”