He and Wesley carried in the chairs.

“She had a painting on that wall over there, and another one to the right of the door leading into the dining room,” I pointed out. “A still life and an English landscape. So Potter couldn’t live with her art but didn’t seem to have a problem with anything else.”

“We need to go around the house and close all blinds, shades, and curtains,” Vander said. “If any light is still coming through, then tear off a section of this paper” he pointed to a roll of heavy brown paper on the floor “and tape it over the window.”

- For the next fifteen minutes, the house was filled with the sounds of footsteps, venetian blinds rattling, and scissors slicing through paper. Occasionally somebody swore loudly when the paper had been cut too short or the tape stuck to nothing but itself. I stayed in the living room and covered the glass in the front door and in the two windows facing the street. When the three of us reconvened and turned out the lights, the house was pitch-black. I could not even see my hand in front of my face.

“Perfect,” Vander said as the overhead light went back on.

Putting on gloves, he set bottles of distilled water, chemicals, and two plastic spray bottles on the coffee table. “Here’s the way we’re going to work this,” he said. “Dr. Scarpetta, you can spray while I videotape, and if an area reacts, just keep spraying it until I tell you to move on.”

“What do you want me to do?” Wesley asked.

“Keep out of the way.”

“What’s in this stuff?” he asked as Vander unscrewed the caps from bottles of dry chemicals.

“You don’t really want to know,” I replied.

“I’m a big boy. You can tell me.”

“The reagent’s a mixture of sodium perborate, which Neils is mixing with distilled water, and three-aminophthalhydrazide and sodium carbonate,” I said, getting a packet of gloves out of my pocketbook.

“And you’re certain it will work on blood this old?” Wesley asked.

“Actually, aged and decomposed blood reacts better with luminol than do fresh bloodstains because the more oxidized the blood, the better. As blood ages, it becomes more strongly oxidized.”

“I don’t think any of the wood in here is salt treated, do you?” Vander looked around.

“I shouldn’t think so.”

I explained to Wesley, “The biggest problem with luminol is false positives. A number of things react with it, such as copper and nickel, and the copper salts in salt-treated wood.”

“It also likes rust, household bleach, iodine, and formalin,” Vander added. “Plus, the peroxidases found in bananas, watermelon, citrus fruit, a number of vegetables. Also horseradish.”

Wesley looked at me with a smile.