NEW HAVEN, Conn. Sept. 26, 2011 -- Dr. William Petit and several of his family members walked out of court today, some of them in tears, unable to listen to the coroner's testimony describing the final moments of his teenage daughter who died in a fire set by a pair of robbers.

Hayley Petit, 17, died along with her younger sister, Michaela, on July 23, 2007, tied to their beds in a suburban Connecticut house splashed with gasoline. Their mother, Jennifer Hawke-Petit, was raped and strangled before the house was set ablaze.

Hayley Petit's body was found at the top of the staircase. Her sister's body was found still in her bed.

The gruesome testimony along with graphic photographs were presented today in the murder trial of Joshua Komisarjevsky, who could face death penalty if convicted. His accomplice Steven Hayes was convicted in a separate trial last year and awaits execution on Connecticut's death row.

Dr. Petit, who was beaten with a baseball bat, was the only person to survive the attack. He has sat in the front row throughout Hayes' trial and sentencing, and has been a fixture at Komisarjevsky's trial.

But today, Dr. Petit left the courtroom before Dr. Malka Shah, who performed the autopsy on Hayley Petit, began her testimony.

Dr. William Petit Has to Leave Trial

Shah said that the cause of death for Hayley Petit was "asphyxia due to smoke inhalation." Prosecutor Michael Dearington asked Shah what the girl likely experienced shortly before her death.

Shah told the court that a victim like Hayley Petit would typically "experience significant pain from breathing in smoke and soot before she died." She also likely felt disorientation, nausea and an inability to breathe shortly before her death.

Shah testified that it could have taken from "a few to several minutes" to die after she started to breath in the searingly hot toxic air. Given the third and even fourth degree burns to her feet, Shah it is likely that the flames got very close to the young girl on or about the time that she died although she could not say if Hayley Petit felt the burns before she died.

Jurors were shown photos of Petit's body taken at both the crime scene and during the autopsy. At one point, Shah stood up holding the a photograph in front of the jury and described Hayley's injuries

"This is her body found at the scene…On her upper legs you can see some recognizable skin…Those are mostly second degree burns, but further down you can see more severe burns," said Shah.

Member of Dr. Petit's family, who had been weeping and consoling themselves in court, walked out of the courtroom as the grisly photos were passed out to the jury.

Several canisters of evidence were also shown to the jury, including the burnt boxer shorts Hayley had been wearing when she died.

Earlier, a detective testified that during Komisarjevsky's three hour long detailed confession of what happened that night, he never once cried or expressed any remorse.

The disclosure came as defense attorney Walter Bansley cross-examined Detective Joe Vitello of the Cheshire, Conn., police department in the trial of Joshua Komisarjevsky.

Bansley asked the detective if Komisarjevsky, 31, cried during his confession, and the detective replied, "Never."

When Bansley asked if Komisarjevsky show any emotion, Vitello said with a tone expressing amazement, "Not once."

The court was shown surveillance photos of Hawke-Petit and her younger daughter Michaela in the Cheshire Stop n Shop on July 22, 2007. Komisarjevsky has admitted to police that he first spotted them as potential robbery victims at the store that day, and later said the pair "looked nice."

The mother and daughter appear eerily vulnerable in the photos, shopping for groceries for a family dinner while being stalked by Komisarjevsky, who followed them home to find out where they lived. They were attacked that night.

Bansley also walked Vitello through the chaotic minutes after a radio call came into Cheshire Police Department around 9:30 a.m. on July 23, 2007. Fire and police raced to the scene, but did not enter the house which by then was in flames. Defense attorneys have tried to point out that they wasted precious time outside the house that morning, and lives could potentially have been saved it they had entered the home earlier.

Hayes and Komisarjevsky were grabbed by police as they tried to flee the scene.

Komisarjevsky's legal team has tried to convince the court that it was Hayes who escalated the violence from a robbery to a triple murder in the hopes of avoiding the death penalty.

Bansley tried to paint his client today as cooperative, even helpful, with police after his arrest. It was Komisarjevsky, Bansley pointed out, who told police that three women remained inside the burning building. Komisarjevsky indicated that one of the women, Hawke-Petit, was likely dead, but the two girls might be found in an upstairs bedroom.

Bansley pointed out that Komisarjevsky got a towel to staunch the flow of blood from Dr. Petit who had been beaten with a baseball bat at the start of the home invasion. Komisarjevsky also got Petit a pillow for his back while he was tied up in the basement.

Petit Trial Testimony Overwhelms Father

However, in earlier testimony it was determined that it was Komisarjevsky who had beaten Dr. Petit into silence with the baseball bat found in the Petit family home at the beginning of the home invasion.

Throughout this morning's testimony Komisarjevsky listened intently, but sat almost casually in his chair, leaning and rocking back in his chair. His father sat in the second row.

The brutal testimony today is all the more poignant for the Petit family as today would have been Hawke-Petit's 53rd birthday. Family members were late to court today as they held a special mass in her honor this morning at a Catholic church.

By 10 a.m. Petit family members filled the right-hand side of the courtroom as they have every day for this trial. They wear small pins showing the name of the Petit Family Foundation despite objections by defense counsel.

At the beginning of today's session, jurors were admonished by Judge Jon C. Blue because several of them had been chronically late.