Elizabeth Laposata

“To determine cause and manner of death, we look at scene investigation, autopsy findings, police and witness statements, and medical history. And using that information, we come up with a differential diagnosis — a list of things that might have happened to that person to cause them to die.”

Establishes the standard forensic pathology methodology she applied in this case

“I was able to come to a definite scientific conclusion.”

States she reached a firm opinion on whether O'Keefe's arm wounds are consistent with dog bites

“No, I'm not a mechanical engineer.”

Concession that forms basis of prosecution's argument against her testifying on vehicle-pedestrian injury mechanisms

“In the back of his head, a little bit to the right-hand side, was a horizontal tearing of the scalp and that's called a laceration, and surrounding that were linear scrapes that were vertical in orientation. So that is an injury pattern, and then you have to think, well, what could cause that injury pattern?”

Establishes the specific wound pattern she identified on O'Keefe's head as the foundation for her analysis.

“The coup contra coup of a falling or being pushed backward has injury patterns where the impact occurred, but then there's also injury patterns 180 degrees opposite from that.”

Explains the coup-contrecoup mechanism of a backward fall: injuries at the impact site and 180 degrees opposite.

“No. It has to be a surface that has some small ridges in it to make those little vertical patterns.”

States that the scraping pattern required a surface with small ridges rather than a perfectly flat surface.

“When those delicate bones are broken, there's bleeding, and that bleeding then goes right down into the upper eyelids. So it kind of looks like you have black eyes, but there has not been any punch to the face. It's only come from the skull fracture.”

Explains the raccoon eyes as secondary to skull fractures from the coup contrecoup mechanism, distinguishing them from direct facial trauma.

“No. The bones were 100% intact. No breaks, fractures, hairline fractures. None of those.”

Absence of any bone injury in the arm undermines the theory that a vehicle struck O'Keefe's arm with enough force to shatter a taillight.

“He would be immediately incapacitated with a decreased level of consciousness once he received that impact on the back of the head. He would not be able to make any purposeful movements.”

Establishes that O'Keefe could not have moved or walked after the head injury, relevant to where and how he ended up on the lawn.

“No. There are no ulcers. It's a normal appearance of what we would call a gross specimen.”

Key forensic finding — absence of Wischnewski ulcers, present in 90%+ of hypothermia deaths, supports ruling out hypothermia.

“He did not experience hypothermia.”

Directly contradicts the death certificate's inclusion of hypothermia as a contributing cause of death.

“No. I can't tell you the amount of force. It was significant, because he had the massive skull fractures.”

Establishes Laposata cannot quantify the force involved, undermining the precision of her death timeline opinion.

“It was medium to large.”

When pressed to quantify force, she offers a vague range that Brennan uses to challenge the reliability of her 15-minute death estimate.

“Yeah, both. It could have been both. Sure.”

Laposata concedes the orbital fractures could have been caused by the basilar fracture radiating forward, not just the brain striking the orbital plates as she testified on direct.

“I didn't look at any of that. I'm sorry. I did not look at any DNA.”

Establishes Laposata did not review DNA evidence from the vehicle as part of her analysis.

“I do not know what caused it. I can tell you what didn't cause it, but I don't know what did cause it.”

Concession that she cannot identify the source of the eyelid injury she discussed at length on direct

“No, I looked at the photos.”

Admits she never measured or requested measurements of the Lexus spoiler height despite opining it was inconsistent with O'Keefe's injuries

“Sure. They just lie there. They can become hypothermic and die.”

General medical proposition that an immobile person in the cold can become hypothermic and die; Laposata separately distinguished this case from the proposed mixed living/dead cooling calculation.

“None.”

Direct, unequivocal answer that X-rays showed zero fractures, breaks, or deformities in O'Keefe's right arm

“We see here the two bones of the arm. There's no injury to them. We see the pelvis bone. There's no injury to that bone. They're perfectly normal. And there's no abnormal soft tissue swelling. It's a normal right arm.”

Laposata narrates the X-ray for jurors, emphasizing the complete absence of skeletal or soft tissue injury

“The upper arm bone is totally normal. There's no soft tissue swelling around it. There's no breakage or microfractures.”

Extends the no-injury finding to the upper arm, ruling out damage along the entire right extremity