Survivors of the Manchester Arena bombing are taking a 'disaster troll' to court after he claimed the attack was staged.
Martin and Eve Hibbert were left with severe disabilities following the 2017 tragedy, which saw 22 people killed during an Ariana Grande concert.
The father and daughter, from Heath Charnock, near Chorley, are bringing a civil claim against Richard D Hall for defamation and harassment - the first such action against a conspiracy theorist in the UK.
Martin was paralysed from the waist down, while Eve was left severely disabled in the blast.
Hall targeted multiple victims, tracking them down to their homes or workplaces.
He was unmasked last October in a BBC Panorama investigation and Radio 4 podcast series.
He reportedly admitted to spying on Eve from a vehicle parked outside her home.
Hall pedals theories online claiming several terror attacks were faked and describes 'tactics' in books and DVDs he's released.
The Hibberts hope to have a restraining order imposed which prevents him making further allegations, and are also seeking damages.
They hope it will set a precedent and protect other disaster survivors in future.
The family's lawyer Neil Hudgell told the BBC: "Martin can be seen as a pioneering trailblazer for others to follow if they feel so minded."
Martin said: "It does sometimes feel like a bit of a weight, so it would be nice to be able to put it to bed and just be able to move on with our lives."
Hall's YouTube channel, which boasts over 80,000 subscribers, was taken down.
His market stall has also been closed.
However, his products and other videos are still available on his website.
In December, Hall added a 'True Crime' section which referred to various events and cases, including the disappearance of Nicola Bulley.
The case against him echoes the action taken against Alex Jones, who was ordered to pay nearly $1.5billion by a US court to families of those killed in the US Sandy Hook school shooting.
He has frequently claimed the 2012 attack was a hoax.
Manchester Mayor Andy Burnham has spoken to Martin about the potential for a new law that better protects survivors from harassment and conspiracy theories.
Last month a report in the Manchester bombing found MI5 missed "significant opportunities" to prevent the tragedy.
Terrorist Salman Abedi was among those killed when he detonated a homemade device at the packed venue, with hundreds also injured.
Manchester Arena Inquiry chairman Sir John Saunders released his findings on Thursday, examining whether MI5 could have done more to stop bomber Abedi, 22.
The report revealed that Abedi, of Libyan descent, was probably helped by other plotters who have never been caught.
Sir John, who led the probe, found he may have smuggled a detonator switch into the UK after MI5 officers failed to take appropriate action on two key pieces of intelligence received in the months before the attack.
He concluded: "There was a significant missed opportunity to take action that might have prevented the attack.
"It is not possible to reach any conclusion on the balance of probabilities or to any other evidential standard as to whether the attack would have been prevented."
This led to an unprecedented apology by MI5 Director General Ken McCallum.
The Mirror has contacted Hall for comment.