Above: Polizeidirektion (Police Headquarters) (detail). Formerly the Hotel Austria, the building was constructed for the 1873 Vienna World's Fair. It was purchased by the city in 1874 to house the police department.

Source: Stadt Wien, Wien Geschichte Wiki (City of Vienna, Vienna History Wiki).

4. The Police (continued)

Even though Krauss could not put the Crown Prince under direct surveillance, he was still able to keep track of Rudolf's comings and goings.

Depending on the weather, Rudolf drove around Vienna in any of three different carriages, often doing the driving himself: a two-wheeled gig, an open four-passenger carriage, and a closed two-passenger coupé which was painted green and black, a colour combination reserved for Rudolf. Royal carriages were colour-coded so that Hofburg sentries could see them coming at a distance and call out the palace guard to present arms.

Every beat cop in Vienna knew Rudolf and his vehicles by sight and was under orders to make a note of Rudolf sightings and report them to police headquarters.

Whether or not Krauss gleaned much useful information from his espionage system, he certainly increased Rudolf's paranoia about who he could and could not trust. Rudolf was well aware that he was under scrutiny.

And then he met Josef Bratfisch.