• The Irish Light repeatedly abused Edel Campbell online and its supporters have threatened her lawyer with "execution".
• This case is thought to be the first where a relative has sued.
A grieving mother and her lawyer have been targeted by an extreme campaign of abuse after suing a conspiracy theory newspaper which falsely claimed her son died from a Covid vaccine.
The Irish Light repeatedly abused Edel Campbell online and its supporters have threatened her lawyer with "execution".
Conspiracy theorists worldwide have used dozens of tragic deaths to spread vaccine misinformation.
This case is thought to be the first where a relative has sued.
The Irish Light included Ms Campbell's son, Diego Gilsenan, and 41 others in an article last year which suggested the "untested and dangerous" Covid vaccine was to blame for the deaths. In fact, the BBC has been told Diego had taken his own life in August 2021, aged 18, and had not been vaccinated.
The campaign of abuse following her legal case has been "nothing short of shocking" and may explain why other relatives have not taken action, Ms Campbell's solicitor, Ciaran Mulholland, told BBC Radio 4's Marianna in Conspiracyland podcast.
"You can understand why a lot of people were incredibly reluctant to go to a solicitor when they saw the backlash with Edel Campbell," he said.
Ms Campbell told the BBC that the Irish Light has "made my life hell" and said she's now fearful of speaking out.
The BBC has agreed not to use a photo of Ms Campbell - or her son - for this story to protect her.
In frequent social media posts over several weeks, the Irish Light and its editor, Gemma O'Doherty, have accused Ms Campbell of "outrageous lies", being "mentally unstable" and involved in a "massive fraud". There are also extreme references to suicide about Ms Campbell.
According to Mr Mulholland, people who support the Irish Light have called for him to be executed or shot, as well as anonymously calling his office and threatening other members of staff.
Ms Campbell and her solicitor decided to bring a civil case against Ms O'Doherty for harassment with defamation, after the paper published a photo of her son Diego Gilsenan and others on the front page under the headline "Died Suddenly".
This tagline has been widely used across social media by conspiracy theory activists to suggest unexpected deaths of young people are related to the Covid-19 vaccine.
In the article that featured Ms Campbell's son, the Irish Light claims that the establishment is not questioning the "mysterious deaths" because "they know exactly what it is: the untested and dangerous injection they forced into the Irish people".
Deaths from Covid vaccines are extremely rare. UK figures record 55 deaths where the vaccine was given as the underlying cause, out of more than 50m people who have had at least one dose.
Among some of the other young people featured by the Irish Light, one died in a swimming pool accident, another from a head injury and a third from meningitis, according to their families.
Ms Campbell says the Irish Light did not contact her for comment about Diego before publication. The BBC also understands that the Irish Light did not contact several other family members of young people featured.
Mr Mulholland said the aim of the legal case is not "retribution" or compensation. "All Edel Campbell wanted was to protect the integrity of Diego, and her family as a whole," he said.
Ms Campbell's legal case has been funded through donations and her lawyer's pro-bono work.
He told the BBC the legal proceedings were launched after various attempts to ask Gemma O'Doherty to remove the images of Diego Gilsenan failed and resulted in an escalation in online abuse.
In July, the High Court in Dublin granted a restraining order that prohibits the Irish Light editor from contacting Ms Campbell and from using or publishing the image of her son for any purpose without his mother's consent.
Abusive posts about Ms Campbell have continued on social media, including from the Irish Light account on X, formerly known as Twitter, which Gemma O'Doherty has admitted to running.
Ms Campbell made reports of harassment to the police - but Mr Mulholland says they are yet to contact or question Gemma O'Doherty about these.
Garda Síochána - the Republic of Ireland's national police service - told the BBC that it "does not comment on named individuals" or "specifics of on-going investigations". It says it continues to "actively investigate the alleged harassment of an individual in the North Western Region" of Ireland.
Ms O'Doherty and the Irish Light have not responded to the BBC's request for comment. However, on social media the Irish Light says the BBC will "do a character assassination" on Gemma O'Doherty because "she exposed the vaccine genocide".
In online posts, Ms O'Doherty denies harassing Edel Cambell and continues to suggest her son's death was sinister or mysterious in some way. She has instructed a solicitor to defend the case brought against her.
The Irish Light is a sister paper of its namesake in the UK, the Light, although they are editorially independent of each other. The BBC previously revealed the UK paper has called for the execution of politicians and doctors. It has links to the British far-right and a German publication connected to a failed coup attempt.
As well as more innocuous features, the Irish Light has published stories promoting conspiracy theories such as "Pfizer knew the vaccine would kill", "Water fluoridation is lowering Irish IQ", "Why manmade climate change is a fraud" and "Irish to become a minority in Ireland".
While Ms Campbell is thought to be the first to sue over a false claim about a vaccine death, the case has parallels with other victims of conspiracy theorists.
Manchester Arena bomb survivors are suing over claims the attack was faked and parents of Sandy Hook mass shooting victims won a landmark ruling against Infowars host Alex Jones.