Just after midnight on Feb.13, 2007, a nightmare began to unfold as flames erupted from the house at 1212 Cedar Ave. in Glassboro, N.J.
Jason Henry, 16, stood outside in the shadows, watching silently as his badly burned father, Stefan Edwards, raced out of their home seeking neighbors for help. Henry's mother was still inside.
Michelle Henry, who was suffering from leukemia, finally staggered out, also burned by the blaze. Rescue workers were devastated by what they saw.
"Mr. Edwards has no clothes on. Has burns over 85 percent of his body, third-degree burns. Mrs. Henry, not much better, severe pain, you have rescue personnel working on them, rushing them to the hospital," Gloucester County Prosecutor Sean Dalton told ABC News.
Police spoke to Jason Henry, a honor student and former Boy Scout. Unlike his parents, he was virtually unscathed, with only a burn on his hand.
Police were immediately suspicious, so they took Henry to the police station for questioning.
With his grandmother at his side, Henry told police about how he had helped both his parents to safety. From the tape of the interrogation, it was clear they didn't believe him.
"Your story is not adding up," Glassboro Police Detective Cpl. Dan Williams told him during questioning.
"Like, I'm really not lying or anything at all, that's ..." Henry replied.
"I think you are. … You're able to walk back and forth through this, two, if not three times, and the only injury you sustain is an injury to your hand. OK? It didn't happen," Williams pressed.
But Henry stuck to his story. "Like I said, that's really how it happened."
"Well, I'm saying that I really didn't do it," he continued. "Like you can ask me a million times. I really didn't do it."
Williams told Henry he would ask a million times if he had to. "I know that you did it," he said. "I'd like to find out why."
After a long interrogation, Henry suggested his parents may have set the house afire for insurance money.
Eventually, he admitted to pouring gasoline throughout the house.
"I feel so bad that they got hurt. There was no intention of them getting hurt at all," Henry said.
But what seemed a cut-and-dried case suddenly turned a lot more complicated after Henry later recanted, saying police had forced his confession.
"I didn't do it," Henry told his grandmother, Margaret Henry, after the police left the interrogation room, where their conversation was recorded by authorities.
"Why'd you tell them you did?" she asked.
"I, what else was I gonna say?" he replied.
Jason Henry's parents would later die from their severe burns. Henry was charged as an adult, accused of arson and murder. He maintained his innocence.
So what really happened? Which story is true? Did Jason Henry burn his house down killing his parents? Or was the former Boy Scout coerced by police into saying what they wanted to hear? Many in the community backed the boy.
"He did recant. He did say that he only said that to get out of the interview and then his statement generally was that he didn't do it after that," assistant Gloucester County prosecutor Dana Anton told ABC News. "He stood by that throughout the proceedings. … A lot of people came out and supported him because he said he didn't do it."
Prosecutors decided to bring in forensic examiners from the Bureau of Alcohol, Tobacco, Firearms and Explosives, or ATF.
The ATF allowed "Nightline" unique access -- an inside look at its efforts to solve an arson case.
They used the newest and most advanced technology available to them in a manner a lot like what one might see on CBS' "CSI: Crime Scene Investigation."
The first time that lead ATF investigator Brian Grove and other agents gained access to the scene of the alleged crime wasn't until nine months after the fire, on Nov. 15, 2007.
The house on Cedar Avenue had been sitting idle. Grove and his team begin their painstaking hunt for clues, videotaping and photographing what remained of the home and taking precise measurements of the rooms.
Local authorities informed ATF that they had found evidence of gasoline throughout the home, including in the parents' bedroom.
As they worked, it was clear that ATF agents weren't simply examining the crime scene. They also collected samples from the carpet and the structure of the house. They took measurements of certain rooms, and they were also interested in the furniture.
The strategy: ATF planned to rebuild the bedroom and hallway leading to the parents' bedroom. They wanted to re-create, as best they could, what happened in New Jersey that day.
The ATF's national arson laboratory in suburban Maryland is home to one of the largest "burn rooms" in the world. The massive facility is the site of an endless number of infernos, where again and again, buildings are built up only to be burned down.
There was no evidence of another suspect in this arson, so prosecutors looked to the ATF's forensics to answer critical questions. Was it likely that the parents set the fire themselves in the hopes of getting insurance money? And if Jason Henry set the fire, had he planned to murder his parents? Or had he been so reckless that either their deaths or severe injury were likely?
Last May, ABC News cameras rolled as construction began on what would eventually be three nearly exact replicas of Stefan and Michelle Henry's bedroom.
Grove described what would happen to the newly built models in the medium burn room, which houses three structures specific to the New Jersey case.
"We will run two tests in each of the these structures, the goal being to get a better understanding of the first two to three minutes of the fire that occurred at the actual house, specifically the conditions in the bedroom where the victims were sleeping at the time the fire started," he explained.
For a time, the ATF investigators acted as contractors, locating and purchasing materials as identical as possible to those used to build the Henrys' actual home.
"What we try to do is replicate the scene as best as possible, so if we can't get the exact door frame or what you have, we try to come as close as possible," Grove said.
Sometimes, it could be challenging to find similar materials. For example, it was difficult to locate mattresses subject to older fire codes.
"We want mattresses that don't have any fire retardant on them. … Our hardest task is trying to obtain those types of mattresses, and manufactures stop making them," said one ATF investigator.
"Our next stop is hotels," he said.
Sensors, to measure everything from gas temperature to flames, were manufactured on site.
"These are going to be placed in the bedroom, probably three or four different places around the bed, and possibly in the hallway, the idea that these people had to get out of bed and to the front door … we will be able to get a better understanding of the conditions they were exposed to during their egress from the house," Grove said of the devices.
The sensors were placed throughout the rooms to record temperatures at each second of the fire.
"This equipment allows us to measure gas temperatures, flame temperatures," Grove explained. "We will get a vertical profile, all the way from the ceiling down to the floor."
ATF investigators also mounted cameras, to document what happens at every angle -- another tool to gather information from the fire.
"We have four camera places, two outside, two inside the structure, and we will take still photographs," said Grove. "It's one thing for an engineer to get on the stand and explain to a jury and try to talk science to a jury. It's another thing to show them a video of what happened."
With a few finishing touches, it was almost time. The structure, re-created with furniture as close as possible to the original home, was ready to burn.
"When we set this fire, we are going to get certain temperatures that we measure, certain heat fluxes. We will never say they are exactly what happened at the night of the fire, but they will be similar," Grove said.
So on June 12 of last year, with computers, cameras and sensors tested and ready to go, and firemen standing by, the test began.
The fire was ignited using an amount of gas the investigators believe is less than that used by the suspect. The flames grew quickly, attacking everything in reach.
Agents manned their stations, studying every reading, while computers documented it all.
The bedroom quickly became hell, reaching 800 degrees in 90 seconds.
Again and again the rooms were burned, and each time, the ATF said the results were conclusive.
"We know looking at a fire like this, and a jury would understand, that if they don't get out of that space in a matter of seconds they are not going to make it, or they are going to be severely burned, which they were," Grove said.
The evidence was mounting that Jason Henry poured gas throughout the home, including in his parents' bedroom, in a manner that prosecutors said could have no other result than severe injury or death.
"There really aren't words to describe what they had gone through in the last moments of their life," Dalton told ABC News. "I don't think anyone can imagine the horror of waking up to flames surrounding your bed, on your bed, and realizing that your chances for survival are nil."
"Mrs. Henry indicated, according to Jason, that she was yelling, 'Oh my God, oh my God.' And for her to have to go through that, in her last moments of her life, after having leukemia, and dealing with that painful disease for many years and having her life end at the hands of her son ... is just beyond my comprehension."
Police say Jason Henry was no stranger to playing with fire having found that he and friends had made videos of themselves setting fires.
"He was familiar with accelerants and how fires reacted," said Dalton. "And the amount of gas that was used especially in the bedroom area and where it was located made it very clear that he was attempting to start a fire that would quickly engulf that bedroom, as well as the entire house. And he accomplished that."
On Feb. 27, 2009, following the ATF investigation and after months of maintaining his innocence, Jason Henry, now older and appearing to have been hardened by jail time, admitted to setting the lethal fires in an attempt to get insurance money.
But his parents had not taken out insurance on their home.
Still, the question remains: Why did Jason Henry meticulously pour gasoline around his parents' bed and give them no chance to escape alive?
He pleaded guilty to two counts of aggravated manslaughter.
The prosecutors believe ATF's work was critical in getting the guilty plea.
"Most cases just get detective work, investigative work. The glamour of the forensics or the CSI, so to speak, is rare. … So a case like this, where we were really able to narrow it down to a science, where we could put it in front of a jury, really strengthened this case," Anton told ABC News.
Dalton added, "ATF involvement was a significant factor in the defense realizing that this was a case that they didn't want to take to trial and certainly was a case that they were looking to try and get the best possible deal for their client."
On April 24, Jason Henry was sentenced to 20 years in prison.
He chose to say nothing at the sentencing, and to this day, he has never fully explained why he poured gasoline around his parents' bed and burned their home to the ground.