This is the 4986th most frequent Polish word.
policyjnego
"Policyjnego" means "police" (adjective form, relating to the police).
Here, 'policyjnego' is an adjective modifying 'radiowozu', indicating that the car is associated with the police.
Widok policyjnego radiowozu na ulicy wzbudzał zainteresowanie przechodniów.
The sight of the police car on the street aroused the interest of pedestrians.
In this case, 'policyjnego' describes the intended use of the equipment, meaning it is for police activities.
Zarząd miasta ogłosił przetarg na zakup nowego sprzętu do użytku policyjnego.
The city council announced a tender for the purchase of new equipment for police use.
Here, 'policyjnego' relates to 'dochodzenia' (investigation), indicating that the investigation is conducted by the police.