Prosecutors say Clara Harris circled around and repeatedly hit David Harris with her speeding car, but collision expert Steve Irwin said that while she made tight circles around the body, she hit it only once.
He said he used skid marks and other evidence to reconstruct the car's speed and route, also factoring in the vehicle's 20-foot turning radius.
"If you get in this car and make a turn and rocket left you can never get back to that mark," Irwin said, describing blood left on the pavement where David Harris' body landed after he was hit the night of July 24.
Under cross-examination, Irwin acknowledged that Harris' 5-foot, 9-inch frame could have extended significantly beyond the blood spot.
"What you're really telling this jury is ... you can't tell them she never ran over that body again because you don't know where the body was," prosecutor Mia Magness said.
"Fair enough," Irwin replied.
Prosecution witnesses have disagreed on the number of times Harris was hit. One said twice, another said five times.
Clara Harris, 44, is accused of running down her orthodontist husband, also 44, in a hotel parking lot after finding him with another woman. Defense attorneys contend his death was accidental.
Irwin told jurors Clara Harris struck her husband and his body fell on the hood of her car. The body then fell from the hood and was rolled over by the driver's side wheels, he said.
Wednesday, the man's daughter, a passenger in the car, testified.
"She stepped on the accelerator and went straight for him," Lindsey Harris, 17, said at her stepmother's murder trial. "He was really scared. He was trying to get away and he couldn't."
The teenager said she partially blamed the affair on her stepmother's lack of attention to her father, but said she told her father he should not leave her stepmother for Bridges, whom she described as fake and "the personification of evil."
Prosecutors say Clara Harris was enraged because her husband chose his mistress over his wife.
Lindsey Harris testified her father was struck once and then her stepmother circled around and hit him two more times, never trying to avoid him. The teenager said she jumped out and hit her stepmother when the car finally stopped.
"She said, 'I'm so sorry. I'm so sorry. It was an accident.' She knew what she did and she wasn't sorry," said the teenager.
If convicted, Clara Harris faces up to life in prison. If jurors determine she acted under the legal definition of sudden passion, they could consider a lighter sentence of two to 20 years in prison.