One Irish woman, who was stalked online, says the same man has done this to at least 80 other women.
Emma was contacted in March 2020 on her Instagram account via comments on her photos taken during a holiday to Egypt.
She replied to to the comments, thanking the man in Egypt for his input, which then "opened the floodgates".
She told Lunchtime Live messages from the man got darker.
"He then proceeded to send me direct messages where he would screenshot all my photos, screen record all my videos [and] send them back to me along with depictions of sexual acts.
"Along with explicit messages of sexual assault of what he wanted to do to me - like rape.
"At first I tried to stand up for myself... but the messages got very dark, so I quickly blocked him".
Emma says the man would then create a new account and message her again, and the cycle would repeat.
"Then he started harassing my friends, who he must have seen when my account was public.
"He then started blackmailing them to try and get my attention: and when that didn't work, he then started to do things like uploading video montages of me, putting my photos on porn websites, creating fake accounts pretending to be me - and then messaging underage girls sexual things".
'Threatened to upload photos of their children'
She says she came across several other women on Twitter he was doing similar things to.
"He would blackmail them by threatening to upload photos of their children on the dark web if they didn't buy him a plane ticket to Ireland.
"We all sort of grouped together to try and work out a way.
"We went to the Guards - the Guards were like 'Look he's foreign, he's not in Ireland we can't do anything.'
"We contacted the ambassador in Egypt who was outraged - he tried to do something, but the Egyptian authorities were like 'There's no Irish girl in Cairo, so we can't do anything'".
In September 2020, Emma was offered a marketing job in the Egyptian capital, which she says she couldn't refuse.
"February 2021... he found out where I lived and worked - and I think that's when it really hit me how dangerous a situation I was in."
Emma went to the Irish embassy, who then went with her to the head of the cyber crime unit in Cairo, to make an official report.
"They promised they would do something, and then 10 days later we heard that he'd been arrested.
"And a month later he started again - he'd been let go - so he's really been carrying on ever since.
"Last week I contacted this number that I was told to contact, and basically I was told that the Egyptian government and authorities wouldn't do anything further".
Emma says she wants to raise awareness "and perhaps raise the question of how social media platforms, and the Government, can help Irish people when there's a situation like this.
"There's definitely a gap in the policy and the safety".
She adds: "The Guards and the police here are unable to do anything because he's foreign.
"I'm not the only victim; there's at least 80 other Irish girls who have been a victim and who still are a victim because he's still doing it to this day."
Anyone affected by issues raised in this article can contact Women's Aid on 1800-341-900 or the Dublin Rape Crisis Centre at 1800-77-8888