Machiavellian justification of murder by a crime boss:
(1) to instill fear
(2) to engender respect
Rational reasons for homicide:
(1) to punish someone who has broken a rule, including holding out or failing to execute an order
(2) to eliminate someone who is informing ("ratting") to the police
(3) during a turf war with another gang
(4) to make an example (and to instill fear)
(5) during a hostile takeover (within or outside of the organization)
(6) for profit
(7) an embarrassment to the organization
Failing to murder someone who "merits" death can have negative connotations for the crime boss and organization.
Homicides that will get a criminal in trouble:
(1) killing of a noncombatant
(2) unsanctioned murder of a fellow mobster
(3) done because of overt paranoia or mental instability
(4) associated with unwanted public attention