Josh's sister Jade told Pat Kenny that she has been subjected to abuse and racist comments regarding the death of her brother.
She was speaking after a Brazilian delivery rider was found not guilty of Josh’s murder earlier this month.
"It was going on before the court case, but it wasn't this much,” Jade said.
"There was Facebook pages being made, sort of like harassment - I'd get the page reported, and then they would make a new one.
"When the trial ended then, that was when there was a lot more of it."
Jade added that the comments have appeared across several platforms.
"I wanted to keep my social media up obviously so that I can get Josh's story out.
"But I had people commenting on my Facebook profile, on my Instagram profile, texting me racist comments - 'He deserved to die, he deserved what he got' - everything like that.
"I have a TikTok page as well, and I posted about things on it.
"They commented on that, there was hundreds of comments on that, but I went through them [and] deleted them."
Jade also revealed how the online conversations about her brother has also extended to the Brazilian community in Ireland.
"A girl that is actually Brazilian... is in a lot of Brazilian groups for Brazilian people living in Dublin and Ireland.
"And she told me that in the groups there was a lot of racist comments about him.
"She said herself 'It's not right' and that she was shocked to see it".
Gardaí had previously said they are closely monitoring “online harassment and abuse” as emotions continue to run high following the acquittal of a George Gonzaga Bento (36) over the killing of 16-year-old Josh Dunne.
Sources said gardaí will discreetly police the event to ensure it passes off peacefully amid rising tension.
“There are issues online with a lot of abuse being levelled at both the bereaved family and Mr Bento. This is entirely unacceptable and it is making this situation even more fraught,” a source said.
“There are garda concerns that this online abuse and harassment could translate into violence on the street, which is something we want to avoid at all costs.”
The source said there were “no winners” in the aftermath of Mr Bento’s acquittal, and it was “a priority” for gardaí on the northside of Dublin city to ensure “racial tensions do not now soar” in the community.
Jade had already spoken in recent days about the online vitriol aimed at her family in the aftermath of the trial.
“We have received an awful amount of abuse since the verdict. I’m deleting all the horrible comments once I see them, but they’re coming back just as fast. There were so many racist comments from people who were saying that Josh deserved what happened to him,” she said.