“Timing bloodstains is very tricky and depends on many environmental factors, so the best I can give you at this point is an educated guess, based on the weather and how dry the blood is in various places in the house,” Nan said. “I’d say sometime Wednesday morning or afternoon. It’s hard to be certain without the bodies.”

“How many assailants were there?”

“The evidence at this time indicates only one. That’s based primarily on footprints in the blood. Unless the assailant or assailants were capable of levitation, it would have been impossible to walk through this kind of carnage without leaving footprints of some kind, even if their shoes were covered with booties.”

Eve noted how carefully Nan qualified her conclusions to cover her ass in case she overlooked something or new information came to light. “Are there any signs of forced entry?”

“Not that we can see,” Nan said.

The CSU chief was covering her ass again. But her preliminary conclusion suggested to Eve that the assailant came in through an unlocked door or window or had a key.

“I can only speculate on the sequence of events,” Nan said. “But based on the law of superposition—”

Eve interrupted. “Layers of artifacts will be deposited by age, with the oldest at the bottom.”

Nan was clearly irritated by the interruption. But Eve was only trying to show the CSU chief that it wasn’t necessary to spoon-feed things to an apparently neophyte detective. Eve knew more than people thought.

“Yes, that’s right,” Nan said, “and it gives us a starting point. Unfortunately, the killer removed evidence, starting with the bodies themselves. He also attempted to clean up some of his work, particularly in the bathroom, with cleansers. But there was just too much blood. So he tried to taint what was left behind with bleach and motor oil, a trick I’m assuming he picked up from all those damn CSI shows on television.”

That explained the odd smell and why it conjured images in Eve’s mind of an overchlorinated pool and an auto mechanic.

“But we can still tell quite a lot by looking at the bloodstain patterns,” Nan continued. “The first attack happened here in the kitchen.”

Eve knew that. The blood was a storyboard, every bit as vivid as comic book panels in describing the action that occurred. That’s because, as Eve learned in her training and through her own reading, there were many different kinds of bloodstains, and each indicated the action that caused the blood to be spilled, including impact or projected stains, passive stains, and transfer stains. A spatter stain, for example, was the result of an external force hitting liquid blood, while a projection spatter was the result of blood propelled by arterial spray or cast off by an object that struck the liquid blood. A saturation stain will reveal where a victim fell and bled extensively. Eve could see right away what happened in the kitchen and said so.

“Tanya was the victim, judging by the height of the projection spatter and the purse on the floor. She came back from her nine a.m. Pilates class and wanted something to eat. That’s when she was confronted by an intruder, who slashed her across the throat, and she fell here.” Eve tapped her foot near the puddle of blood. “But she didn’t bleed out here or there would be a lot more blood.”