Moretti

Moretti aka "Moretti the Murdered" is a member of the Vongola family with the skill to stop his own heart, so that he appears to be dead. He was first introduced as part of a test made by Reborn for Tsuna to see how Tsuna would react if he thought he killed somebody. Later, Moretti appeared during the CEDEF invasion into Vongola HQ. Moretti had be working as a spy in Vongola HQ for Iemitsu. He was able to sneak up on a Mosca prototype by stopping his heart, thusly he was invisible to the Mosca's life sensors and able to shut it down. He then warned the CEDEF that the Gola Mosca that the Varia had received was not a prototype and had no off switch, so that if it rampaged it would be "unstoppable".

First Appearance: Chapter 19; Episode 28 Source: http://reborn.wikia.com/wiki/Moretti