Lorenzo Fabbri is the first Italian commisar of the series. He is son of an Austrian woman and an Italian man; after the separation of his parents he lived in a short time in Vienna along his mother, before returning to Italy. Here, he studied law and joined the police.

Lorenzo almost always dresses with dark clothes, in a casual way, without excesses, but without any slovenliness either. He hates neckties and sneakers. He prefers wearing jeans, shirt and jacket, the last item being rigurously black.

In season 11, Rex moves to Rome, where he meets his new partner, Italian homicide detective Chief Inspector Lorenzo Fabbri. Rex seems to understand the Italian language quite easily. In the second episode of season 14 (entitled Amidst the Wolves) Fabbri dies in the explosion of a car during a trap prepared by Donato Tramontana, a Mafia boss.