A triple game

Dr. Miriam Girelli, a famous notary, calls Sant'Andrea confessing to having killed a thief in self-defense. Walter, Sciacca, Nicoletta and Dr. Mari find the body in the villa with a necklace and a gun next to it. The husband reveals that the victim was a member of the squash club. There are no signs of forced entry, but the thief has disappeared from the security footage.