Sachs wanded with the alternative light source – Samantha’s body, the ground of the octagon, the tunnels. Again, Unsub 11-5 had punched and probed her flesh. She noted from the bootie prints that the unsub had walked up and down the tunnel several times to and from the debris pile, which seemed curious, and she told Rhyme. Maybe because he’d heard intruders, he suggested. Or maybe he’d left some of his gear at the mouth. She took pictures and finally returned to the access door, muttering thanks once more to no one in particular that there was nothing claustrophobic about this search.

Once on the outside again, she handed off to the other CS techs, who had finished with the secondary scenes. Detective Jean Eagleston reported the not-surprising news that any of the perp’s movements around the train tracks and the entrance to the tunnel from the outside were obliterated by the rain and sleet.

Aside from what presumably had been a brief struggle in the women’s room, there were no signs that he’d touched anything. There were no tool marks in the screws he’d removed to gain access to the bathroom. And no footprints either, except those of dozens of street shoes – from the people who’d used the toilet.

The sleet beat an irritating drum tap on the hood she wore and she told Rhyme she was disconnecting the video camera for fear the moisture would short out the expensive, high-def system.

She returned to her car, where she filled out chain-of-custody cards for each item collected, working under the trunk lid to keep the cards and evidence bags dry. Stripping off the Tyvek suit, she slipped it into a burn bag in the crime scene van and returned to the street, pulling on her leather jacket.

Sachs noticed Nancy Simpson, the detective, speaking to Bo Haumann. The other officers who’d gone off in pursuit of the fish were straggling back.

Haumann rubbed his grizzled crew cut as Sachs walked up. ‘Nothing. Nobody saw him. But—’ He glanced up at the inhospitable skies. ‘Not a lot of people out tonight.’

She nodded then headed over to Lon Sellitto, who was talking to a group of people about Samantha’s age. She told him about the pursuit – of the unsub or an innocent voyeur – the unsuccessful pursuit. He took the news with a grunt, then they both turned to the others, who were, the detective reported, Samantha’s fellow diners. She’d deduced this earlier from their expressions.

‘I’m sorry for your loss,’ Sachs said. One woman’s face was streaked with tears – a co-worker. The other woman, a blonde, looked put out and uneasy. Sachs guessed she had coke in her purse. Let it go.

The two men were angry and resolute. None of these had been Samantha’s lover, it seemed. But one was her roommate; the greatest sorrow within the four resided in his eyes.