Dutch source for story comes from Amsterdam Post:
http://www.amsterdampost.nl/een-brief-van-een-antwerpse-moeder-aan-een-marokkaanse-moeder/
Gates of Vienna still trying to authenticate the story. The only new factoids so far are that Timo, the translator of the letter, says it’s authentic, and says it is at least plausible because recently there were riots in some Belgian prisons and supposedly an independent story about a Moroccan mother complaining about her son being moved to a more distant prison.
Dunno.
Verification would be a snap - incredibly easy:
1. Name of prison perp would be public record.
2. News article with name of mother complaining would be avaiable which would once again provide name of prison perp.
Since OP references blogger who references Dutch blogger who references so-and-so who personally vouches authenticity without providing names...etc...
...it’s fiction aimed at those who are gullible and ready to believe anything that tugs certain strings.
=8-)