RIVERHEAD, N.Y. (CBSNewYork) — The defense launched its case Monday in the drunk driving trial of the Holbrook man accused of striking and killing 12-year-old Boy Scout Andrew McMorris.

Thomas Murphy is accused of being legally drunk hours after the crash when his blood was drawn, but a defense expert testified that reading was flawed.

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A Long Island man who admitted to killing a Boy Scout while driving drink is due in court today. (CBS2)

Forensic toxicologist Dr. Jimmie Valentine, an expert in blood alcohol testing, poked holes in the centerpiece of the case against Murphy — his .13 blood alcohol content reading four hours after he crashed into a pack of Boy Scouts.

“The bottom line is it’s an uncertain measurement. It’s not to be trusted,” defense attorney Steven Politi said.

Valentine cited a litany of problems with the way it was collected, stored and analyzed, saying problems with the collection can lead to problems with the reading, CBS2’s Carolyn Gusoff reports.

Because Murphy had high blood sugar, that could elevate his blood alcohol level, Valentine said. Fermentation in the body can turn sugar into alcohol.

“The sample was not giving the correct value,” Valentine said.

“Mr. Murphy was not intoxicated in any way, in any shape,” Politi said. “There is evidence to suggest that his BAC is below .08.”

Andrew McMorris (credit: Suffolk Council Boy Scouts Of America)

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“This is a terrible display of the loopholes of our system and what’s going on in there is just a disgrace,” Alisa McMorris, the victim’s mother, said.

John McMorris, who was steps behind his son on the fateful hike, says he heard Murphy unable to speak clearly.

“It’s indisputable what he did that day with the witnesses, what they saw, what I saw. This is no question that man drank, he got into a vehicle and crashed into four boys,” he said.

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Murphy is now facing four fewer charges.

Judge Camacho, as expected, tossed out four top counts related to an even higher blood alcohol content due to reasonable doubt.

“The judge had to dismiss the charges because what they alleged was false,” Politi said.

The defense is still considering putting Murphy on the stand. His repeated apologies through a previous attorney are not admissible in this trial.

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Murphy still faces the possibility of 8-25 years in prison if convicted even though some of the charges were dropped.