France, May 23 -- Can you take the law into your own hands? The law itself says no. But vigilantes who do just that are rife on the internet and, thanks to social media, their numbers are on the rise.

Child sex offenders are their prime target. French streamer FINNYZYY has generated headlines over the last week after ensnaring Dominique B, a 66-year-old retired sports teacher who believed he was talking to a 14-year-old girl online.

In reality this was FINNYZYY, using artificial intelligence tools to generate the face and voice of a young girl during their video calls.

Like others who have been similarly caught out, Dominique B had steered the conversation towards sexual topics, asking the "girl" if she would like to kiss him and see h...