Noun
pentito (plural pentiti)
A criminal who cooperates with police or government authorities and testifies against or provides harmful information on fellow criminals; a turncoat or informant, usually a former Mafioso. [from 20th c.]
Since the pentito himself is physically protected by the police, retribution on his family is common; therefore, when there are rumours of a mafioso collaborating with the police, the family usually condemns that person immediately to avoid retaliation. Source: Internet
The word pentito implies a moral judgement that is considered inappropriate for the courts of justice to make. Source: Internet