WATERVILLE — The chemical that police used to discover the blood of Ayla Reynolds in her home can literally shed light on an investigation.

The liquid, luminol, can be used to detect trace amounts of blood that would otherwise be invisible.

Even when blood is cleaned from a surface, traces that can’t be seen remain. When luminol comes into contact with blood, it glows.

Steve McCausland, spokesman for the state Department of Public Safety, said during the weekend that in December investigators found blood from the missing toddler in the home where she was reported missing on Dec. 17. He wouldn’t disclose how much blood, but said investigators used luminol to find it in the basement at 29 Violette Ave.

The chemical was first used for forensic purposes in 1937, said Melisa Staples, assistant director of the New Hampshire State Police Crime Laboratory in Concord, N.H. It reacts with several materials, including cleaning products, some metals, and horseradish, she said.

For that reason, a chemical reaction doesn’t necessarily signal the presence of blood.

Staples said investigators typically use the chemical toward the end of a crime scene investigation, after other potential evidence has been removed..

“When you spray it on, you see a glowing bluish light when there’s a positive reaction,” she said. “That light then dissipates, so you need to be able to photograph it right away and make your observations very shortly after you spray it.”

Investigators get only one chance to detect blood with luminol. Once the two have reacted, they won’t react a second time.

If investigators get a positive reaction, the next step is to get samples to the crime lab.

McCausland said Saturday that several hundred pieces of potential evidence were removed from Ayla’s home, including blood samples that haven’t been tested.

“We think the three adults in the home that night haven’t told us everything they know,” McCausland said Saturday.

He said Monday that six people were in the house on the night before Ayla was reported missing: Ayla and her father, Justin DiPietro; DiPietro’s sister Elisha DiPietro and her young daughter; and DiPietro’s girlfriend, Courtney Roberts, and her young son.

Justin DiPietro declined to comment Monday, brushing past an Associated Press reporter outside his house without addressing questions.

Morning Sentinel Staff Writer Ben McCanna can be contacted at 861-9239 or at: bmccanna@centralmaine.com

 

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