The other investigating detectives were Wilhelm Wurth, a sergeant who was a big noise in the police sports movement, and Gottfried Lehnhoff, an inspector who had returned to the Alex after having retired.

Wurth was in the fencing team, and the previous winter he had taken part in Heydrich’s skiing competition for the German Police and won a medal. Wurth would have been in the Army but for the fact that he was a year or two too old. But he was a useful man to have along on a murder investigation in the event that the victim had skied onto the point of a sword. He was a thin, quiet man with ears like bell-pulls and an upper lip that was as full as a walrus moustache. It was a good face for a detective in the modern Berlin police force, but he wasn’t quite as stupid as he looked. He wore a plain grey double-breasted suit, carried a thick walking stick, and chewed on the stem of a cherrywood pipe that was almost always empty but somehow he managed to smell of tobacco.

Lehnhoff had a neck and head like a pear, but he wasn’t green. Like a lot of other cops he’d been drawing his pension, but with so many younger officers now serving in police battalions on the eastern front he had come back into the force to make a nice cosy corner for himself at the Alex. The little Party pin he wore in the lapel of his cheap suit would only have made it easier for him to do as little real policing as possible.

We walked south down Dircksen Strasse to Jannowitz Bridge and then along the S-Bahn line with the river under our feet. There was a moon and most of the time we didn’t need the flashlights we’d brought, but we felt safer with them when the line veered back over the gasworks on Holtmarkt Strasse and the old Julius Pintsch lighting factory; there wasn’t much of a fence and it would have been easy to have stepped off the line and fallen badly.

Over the gasworks, we came across a group of uniformed policemen and railway workers. Further down the track I could just make out the shape of a train in Schlesischer Station.