Sheriff
You have exact checks, but no automatic trust from the table. On the first night check two players, then one at a time, and decide when to pass your information to the city.
The Sheriff has the strongest reliable source of information in the city, but does not control the trust of the other players and may die before revealing themselves in public.
The first night: two checks
Choose two different players. You can give priority to those whose roles will most affect tomorrow's vote: influential participants, conflicting candidates, players with contradictory positions. A random choice is also possible, but it is not a required optimal strategy.
Two checks of two different players. Options: two key disputed participants; one suspect and one potential anchor player; two figures from rival day coalitions. No choice guarantees success.
What the colour means
The result "Irish" or "Italian" is a reliable affiliation of the checked player at the time of the check. "The city" is not necessarily an ordinary civilian: it may be a representative of the city, including the Sheriff as a type of role, though the Sheriff does not check themselves. A check does not tell you who the boss is inside a gang, unless the rulebook specifically provides it.
The following nights
One check should reduce uncertainty, not just confirm your own liking. Avoid re-checking a living player who was already reliably checked, without a special reason. When the numbers of the teams change, the value of different checks changes.
Three modes of revealing
Staying hidden: keep checking, if there is a chance to build up information safely. An early reveal: give the results when the city risks voting out a checked civilian or when the vote must be changed urgently. A delayed reveal: present a consistent chain of results when the information has built up and there is a chance to convince the table. No single mode is universal.
Revealing against two gangs
If representatives of both gangs have been checked, do not just say "both are mafia"; give their affiliations separately. This lets the city see that one attacking the other in public may be a real conflict of rivals, not proof of the attacker's honesty. Offer a reasoned sequence of decisions, but do not present unknown roles as checked.
The false Sheriff
A rival may claim checks. Compare the timeline, the number of checks, the colours named, earlier speeches and votes. The real Sheriff does not get automatic confirmation from the host; the table must judge the competing versions.
Answer with facts and consistency, not an emotional attack. Compare earlier public statements with the possible checks.
Death at night
The Sheriff may get the result of their check on the night of their death, if the order of the host's actions provides for it, but will not be able to report it after dying. The exact order of simultaneous actions is set by the rulebook (needs confirmation).
Typical mistakes
Revealing yourself with no clear aim; presenting a guess as a check; not naming the exact colour; thinking that a checked mafioso is surely a leader; forgetting that both bosses are looking for the Sheriff in particular.
Do not present suspicions as results of checks; do not promise a certain win after revealing; do not forget that both gangs can hunt you.
Interpretation
The result "the city" confirms membership of the team but does not make a player an infallible analyst. "Irish" or "Italian" does not automatically say whether the player is the leader of the gang.
Hidden play
Silence lets you build up checks but risks dying without passing on the data. Weigh the threat of a day removal and a night kill.
An early reveal
It is worth considering when your own removal is threatened, when you have two important finds or when the numbers are critical. A reveal should contain a timeline: the night, the numbers, the exact colour, and then, separately, the assumptions.
Two gangs found
If you have found an Irish and an Italian player, do not become an ally of one side. The aim is to destroy both gangs, and the order of voting depends on risk and numbers.