DNA that matched murder defendant Marty Roe's DNA profile was found on the trigger and hand grips of the semiautomatic pistol that was used to shoot Lexington dermatologist Dr. Martha Post, a forensic biologist testified Tuesday.
Kentucky State Police forensic biologist Alison Tunstall's testimony provided more details about how police linked Roe to Post's killing. Tunstall also was one of the prosecution's last witnesses to be heard before it rested its case. Prosecutors called 40 witnesses over five days.
The defense began presenting its case Tuesday. If all goes as expected, instructions to the jury and final arguments will be heard Wednesday after lunch, and the jurors will begin deliberations.
On Tuesday, the prosecution and defense peppered Tunstall with questions about DNA — and whether it could be transferred.
Tunstall told jurors the DNA profile would be found in only one in 770 trillion people. There are an estimated 7 billion people on Earth.
Investigators say the gun, a Bersa .380, was found in the engine compartment of Roe's van after he was arrested in Lakeview, Ohio, and charged with murder in September 2011.
Under cross-examination by defense co-counsel Robert Friedman, Tunstall couldn't say how Roe's DNA got on the gun. She acknowledged that it is possible it got there by "secondary transfer."
"You have no reason to deny, do you, that by wearing a glove, I can pick up someone else's DNA and deposit it on a surface?" Friedman asked.
Tunstall's response: "No, that's possible."
The defense's line of questioning is meant to suggest that police, during their search of the van from back to front, might have inadvertently transferred Roe's DNA from other evidence and onto the gun.
But Detective Phil Bailey of the Logan County, Ohio, sheriff's office testified during defense cross-examination on Monday that he put on a new pair of gloves with "every item I collect," and followed that protocol while gathering evidence from Roe's van. The collected evidence was then handed over to Lexington police.
Post was shot three times on Sept. 1, 2011, as she backed her van out of the parking lot of her office on Huguenard Drive.
The prosecution has said that Roe, a former handyman in Post's building, was obsessed with Post, and when she didn't reciprocate his affection, he shot her.
The defense has said that Post's husband, Dr. Robert Truitt, stood to gain from her death with a $1.5 million life insurance settlement. But Lexington police detectives have testified that Truitt was excluded as a suspect as the evidence pointed to Roe.
Tuesday's final prosecution testimony came from a series of Kentucky State Police forensic specialists in DNA, fingerprints and firearms.
Lawrence Pilcher, a firearms examiner, said the three spent shell casings found at the shooting scene had microscopic grooves that matched others fired from the Bersa at the state police lab.
Fred Crane, a latent fingerprints examiner for state police, said no prints of value were found on the gun. Crane said that wasn't surprising because prints, which are fragile, can be lost in places where it's hot, such as beneath the hood of a van.
Dr. Kristin Rolf of the state medical examiner's office in Frankfort was the last prosecution witness. She performed the autopsy on Post, and testified about gunshot wounds to the neck, chest and left thigh. She said the chest wound was the lethal injury in that it tore through the heart, right lung and liver, and led to a large loss of blood.
When the defense began its case Tuesday afternoon, the first witness called was Courtney Mitchell, who was a physician's assistant in Post's dermatology practice.
During cross-examination, Assistant Commonwealth's Attorney Brad Bryant asked Mitchell: "From what you have seen, was Dr, Post in love with him (Roe)?"
"No," Mitchell said.
On redirect examination, defense co-counsel Shannon Brooks-English asked Mitchell: "Was Dr. Post afraid of him (Roe)?"
"Not while I was there," Mitchell said.
The defense is expected to call several more witnesses when the trial resumes at 9 a.m. Wednesday.
Greg Kocher: (859) 231-3305. Twitter: @HLpublicsafety.