Lindsay Clancy strikes evidence deal as fingerprint gap opens trial debate, expert says

Lindsay Clancy spoke directly in court Tuesday, repeatedly answering, "Yes, Your Honor," as she agreed to let prosecutors treat certain forensic facts as established hours before a state police trooper testified that investigators recovered no usable fingerprints from a knife or three exercise bands.

The developments narrowed the Massachusetts mother’s murder trial toward its central dispute: whether Clancy was criminally responsible when her three children were killed inside the family’s Duxbury home.

Before jurors entered the courtroom, Judge William Sullivan questioned Clancy about a stipulation covering certain evidence.

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"You understand that by signing the stipulation, you’re agreeing that the Commonwealth does not have to prove these certain facts that are contained in the stipulation," Sullivan said. "Do you understand that?"

"Yes, Your Honor," Clancy replied.

Asked whether anyone had forced or threatened her to accept the agreement, Clancy said, "No, Your Honor."

Sullivan found that Clancy was competent and had entered the stipulation "knowingly, intelligently, voluntarily and willingly."

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Defense attorney Kevin Reddington said the agreement would prevent prosecutors from calling dozens of witnesses solely to establish the chain of custody for blood, bodily fluids, exercise bands and DNA evidence.

"We have not been contesting the government’s case in chief, if you will," Reddington said.

The stipulation is not a guilty plea or an admission that Clancy was criminally responsible for the deaths of Cora, 5, Dawson, 3, and Callan, 8 months.

WATCH: Former prosecutor explains strategy behind Lindsay Clancy evidence agreement

Margaret McLean, a former criminal prosecutor and trial attorney who teaches law at Boston College’s Carroll School of Management, said the agreement allows the defense to steer jurors away from repetitive forensic testimony and toward Clancy’s mental state.

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"The legal strategy behind the move by the defense is to steer the jury’s focus away from the horrific nature of the acts and to that central issue of criminal intent, or what we would call mens rea," McLean told Fox News Digital.

McLean said Clancy’s measured responses Tuesday should not be taken as evidence of her mental condition on Jan. 24, 2023.

"She sounded rational. She understands what she’s doing," McLean said. "But remember, the Commonwealth’s burden of proof is to prove that she was sane beyond a reasonable doubt at the time the crimes were committed -- not today, not two weeks ago."

WATCH: Trooper details crime scene evidence collection at Lindsey Clancy's home

Later, Massachusetts State Police Trooper Jonathan O’Loughlin testified about examining a knife and three exercise bands collected from the home.

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O’Loughlin said the knife contained an area of friction-ridge impression, but investigators could not use it to identify anyone.

"There was not enough characteristics or minutia to do any comparison," O’Loughlin said, adding that the impression had "no value."

The yellow, black and blue exercise bands similarly produced no impressions suitable for comparison.

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"The bottom line is that you didn’t get any fingerprints," Reddington said.

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"Correct," O’Loughlin replied.

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O’Loughlin said fingerprints are "very, very, very fragile" and can be affected by an object’s texture, environmental conditions, movement, grip strength or whether a surface was wiped.

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McLean said the absence of identifiable prints could make jurors wonder whether gloves were used or the items were wiped, potentially viewing the missing prints as evidence of planning.

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The defense, she said, can counter that jurors must not "speculate on something that’s not in evidence."

"They can use their common sense when they go to the table and they deliberate," McLean said, "but they can’t speculate [about] things that are not in the evidence."