Hint 1. It involves the police station
Hint 2. It involves giving something to the inspector
Hint 3. It involves giving something unusual to the inspector
Solution. Give the knife to the inspector.
It’s hinted at in-game. You know from the storyline that you have been resurrected for some purpose. If you EXAMINE KNIFE, it tells you that it’s ‘the object capable of bringing you to existence’, so it’s worth finding out more about this object. If you ASK BARMAN ABOUT KNIFE, he suggests that “…The Inspector’ll be real keen on getting it back…”