Expert: Double-fatal crash caused by speed, oversteering, alcohol
A retired state police expert crash reconstructionist testifying for the prosecution in the manslaughter trial of Jodie L. Tierney said Stone Hill's SUV was going between 64 mph and 73 mph when the driver lost control.
Andrew Thierwechter said he concluded the crash was the "result of excessive steering for the speed traveled, exacerbated by alcohol impairment of the operator."
Chief deputy prosecutor Tim Barker called Thierwechter to the stand Tuesday morning to testify about his review of the June 16, 2015, crash on Slab Road in Lower Chanceford Township that killed Stone, 17, and 16-year-old Nick Mankin.
After going out of control, Stone's Toyota 4Runner crashed into a utility pole and burned beyond recognition, according to earlier testimony. Stone and Nick were likely already dead from blunt-force injuries, a deputy coroner has testified.
Sobering studies: Thierwechter cited a study that among male drivers ages 16 to 20, a blood-alcohol-level increase of 0.02 percent is estimated to more than double the relative risk of a fatal one-vehicle crash.
He said another study has shown that male drivers ages 16 to 20 are 52 times more likely to be involved in fatal crashes than sober males in the same age group.
Thierwechter told jurors Stone's SUV was eastbound on Slab Road, approaching a slight right curve in the road, followed by a significant left curve in the road. Where the road curves left, there's a slight downgrade, he said, and it's about 520 feet from the start of the right curve to the spot where the 4Runner crashed and burned.
The SUV went up an embankment on the opposite side, barely missing a utility pole, then came back down and into the center of the road, he testified.
Oversteered: The driver then oversteered again, causing the SUV to again leave the road from the opposite side and crash into a second pole, shearing it off and moving the base about 18 inches in the ground, he said.
Stone's blood-alcohol level was later determined to be 0.094 percent. In Pennsylvania, an adult is driving drunk at 0.08 percent. Nick's blood wasn't tested because police believe he was the passenger and that Stone was driving.
The case: Tierney, 46, of Percheron Drive in Windsor Township, is accused of allowing her high-school-age son and his friends to drink alcohol at her home without rules or repercussions.
Stone and Nick were among a group of teens who attended a party there the night of June 15, 2015, then slept over. The next morning, they woke up and started drinking again, according to testimony.
Stone had four or five shots of rum as well as beer in the hours before the crash, according to testimony.
Tierney remains free on bail, charged with two counts each of involuntary manslaughter and child endangerment, and one count each of corruption of minors and furnishing alcohol to minors.
Defense case: Defense attorney Doug Bare called his first defense witness Tuesday afternoon — Dr. Lawrence Guzzardi, who was director of York Hospital's emergency department throughout the 1980s and who is now a medical expert at trials in areas including medical toxicology.
He testified Stone's BAC is unreliable because it was taken in an unusual way and because the sample could have been contaminated.
"If the heart is damaged, especially if there's contamination ... from the stomach, then any specimen obtained from the heart is contaminated," Guzzardi testified, adding it could falsely elevate the alcohol reading.
But during cross-examination, chief deputy prosecutor Tim Barker got Guzzardi to admit that when he prepared his expert report based on his review of the case, he erroneously assumed Stone's blood was taken via the "blind-stick" method, which involves placing a needle at a specific rib and inserting it a specific way.
Blood draw: The morgue worker who drew the blood testified last week that he went in through an incision and stuck the needle directly into the heart. Guzzardi testified he had never heard of that method being used.
Barker also got the doctor to admit he didn't take into consideration witness accounts of Stone's drinking that day, or view Snapchat video of Stone drinking.
Guzzardi, on redirect, said none of that changed his opinion that Stone's BAC result is unreliable.
Barker also made sure jurors knew that on Wednesday, Guzzardi is participating in a lecture about "DUI: Strategies to Win the Case," to discuss with defense attorneys deficiencies in field-sobriety testing.
Guilty plea: Tierney's husband, Stephen D. Tierney, 46, pleaded guilty last week to corruption of minors and furnishing alcohol to minors. He had been scheduled to stand trial with his wife.
His charges of involuntary manslaughter and child endangerment will be dropped at his Aug. 21 sentencing, according to the judge.
— Reach Liz Evans Scolforo at email@example.com or on Twitter at @LizScolforoYD.