DUMBEST BURGLAR IN THE WORLD

It's obvious how this dumb thief was caught and sent to prison. (stupid is grammatically correct but doesn't sound right here.)
A man who had tried to assault a seven years out of service bank office using a toy gun, and take a pedestrian hostage(You can use pedestrian as a hostage, but to fit the flow of the sentence I'd just put pedestrian hostage.), has been sentenced to seven years in prison by the Court of Justice in the german city of Osnabruck.
Named as “the dumbest burglar in the world”(Stupidest can be viewed as a more European term.) by local press, he entered a building that he thought was a bank office. However, this office had ceased its activity seventeen years ago. When he noticed that it was actually a physiotherapy center, he toook a pedestrian hostage, and forced her to take cash from the buiding lobby's automated teller machine.
But this wasn't the end of the story. Once he got four hundred euros from the hostage, he escaped in his car. In his haste, however, he'd forgotten the toy gun covered with his fingerprints in the back seat.
When caught, he confessed to all charges (You can actually say confessed in this context, I'm just showing an alternative way of saying the same thing.) and now he will have to pay for twenty two crimes commited.(Do you mean he will be in jail for his crimes or he will have to pay a fine? Or that he will have to go to court for his crimes?)

(Overall, a good post. Had a few minor errors, but very good quality overall. :D)

Oh y muchas gracias por editar mi propio escrito :D