She preferred to leave her heart unguarded.

‘I’ll collect it last,’ Sachs told him. ‘Every bit of light helps.’

She then walked the grid, which was Rhyme’s phrase for searching a crime scene. The grid pattern was the most comprehensive approach in looking for evidence and assessing what had occurred. This technique involved walking slowly across the scene, then pivoting and moving one step to the right or left and returning to the far side. You did this over and over until you’d covered the entire space. Then you turned 90 degrees and covered the same ground again, perpendicular. Like mowing a lawn twice.

And with each step you paused to look up and down and side-to-side.

You smelled the scene too, though in this case Sachs couldn’t detect more than Chloe’s vomit. No methane or feces, which surprised her, considering that one of the pipes here was connected to the city’s sewage system.

The search didn’t reveal much. Whatever implements the perp had brought with him he’d taken – aside from the flashlight, cuffs and strips of duct tape. She did make one find, a small ball of crumpled paper, slightly yellowed.

‘What’s that, Sachs? I can’t see very clearly.’

She explained.

‘Leave it as is; we’ll open it back here. Might have trace inside. Wonder if it’s from her.’

Her. The Vic.

Chloe Moore.

‘Or maybe from the perp, Rhyme,’ Sachs added. ‘I found what looked like fibers of newsprint or paper under her nails.’

‘Ah, that could be good. Did they fight? Did she grab something of his? Or did he want something she had and rip it from her fingers – while she struggled to hold on to it? Questions, questions, questions.’

Using additional adhesive rollers and a small handheld vacuum, Sachs continued the search. Once these samples had been bagged and tagged she used a separate vacuum and a new roller to collect trace from places as far away as possible from where Chloe lay and where the unsub had walked. These were control samples – natural trace from this area. If analysis back at the lab revealed, for example, a clay-rich earth near one of the unsub’s footprints, which didn’t match any control specimens, they could conclude that he possibly lived or worked in or had some other connection to a locale loaded with clay. A small step toward finding the perp … but a step nonetheless.

‘I can’t see many shoe or boot marks, Sachs.’

She was looking down at where he’d stood or walked. ‘I can make a few out but they’re not going to be much help. He wore booties.’

‘Brother,’ the criminalist muttered.

‘I’ll roll the footfalls for trace but there’s no point in electrostaticking.’