Marijke had said nothing, unwilling to provoke further her boss’s prejudice against university graduates like herself. Although Maartens was every bit as clued in about modern policing as any of his colleagues, he still clung to some of the old-school attitudes of his youth, and she didn’t want what was an already complicated investigation made any more awkward. She’d acknowledged his assignment of the university connection to her team with a quick nod. It would almost certainly be a complete waste of time, and it would have to wait until after the weekend, but she’d make sure the job was done thoroughly.

Tom Brucke’s team had begun their canvass of the neighbourhood, but so far they’d drawn a blank. Nobody had seen or heard anything that had any apparent relevance to the murder. It wasn’t the sort of area where a strange car would immediately be noticed by the neighbours, and few people paid attention to individual pedestrians on a street where there was regular foot traffic. Whoever had killed Pieter de Groot, he hadn’t drawn attention to himself.

Marijke had spent the rest of the day supervising a search of de Groot’s home, to see if there was anything that might be construed as a clue to the bizarre scenario that had been played out in the upstairs room. But there was nothing. She wondered about what was missing, however. There was no sign of a diary, desk calendar or personal organizer in the office. She couldn’t believe a man like de Groot wouldn’t have some sort of aide memoire for his appointments in his home office. She’d even had one of the technicians check over his computer to see if he kept an electronic diary, but that had drawn a blank too.

But sometimes absences held their own clues. To Marijke, this lack said that whoever had killed Pieter de Groot was no casual caller. He’d been expected, and he’d taken care to remove all trace of that appointment. If she was right, there was a chance that there might be a duplicate note of the arrangement in de Groot’s diary at the university. She made a note to herself to make sure she was there when they entered his office, and set one of her officers the task of getting them admission first thing in the morning.

Eventually, she grudgingly accepted there was nothing more for her to do. Her team was busy with the tedious routine of sifting material and information that would probably prove useless. They didn’t need her. The best way she could serve the inquiry now was to go home and let her mind turn over what little they knew. Sleep, she always found, was the best possible state in which to uncover new angles of approach.