The police suspect someone. I can't reveal whom the police suspect. The police never found out who the axe-murderer was. Pierre was the last to know whom his wife had taken as a lover. We couldn't see who was firing at us.
Someone is in the driver's seat.
Whoever is in the driver's seat bears responsibility for the auto. Responsibility for the auto is in the hands of whoever is in the driver's seat. You can trust whoever comes bearing this ring. You can trust whomever I will send. Someone damages my reputation.