He has spoken

He may want to take into account that the person being accused in court of fraud is not the one he implied was responsible for the alleged fraud in the Egrant matter but his best friend, and the man he appointed to be the most powerful man in the land during his administration.

Police Commissioner Lawrence Cutajar

Arnaud investigates Arnaud

The people within the knowledge group for this case would normally be Arnaud’s immediate superior – assistant commissioner Kevin Farrugia, the police commissioner Lawrence Cutajar, obviously Inspector Arnaud himself, and possibly Arnaud’s right-hand man. Joseph Muscat and Keith Schembri should not have been privy to the information, but they were. That’s five or six people in all.
It shouldn’t be hard to figure out who leaked the information.