A forensic expert today revealed he found 'shockingly high' levels of chloroform in the boot of Casey Anthony’s car after it was confiscated in the hunt for her missing daughter.
Dr Arpad Vass, an expert in human decomposition at the Oak Ridge National Laboratory in Tennessee, told a court in Florida he had never seen such high levels in his 20-year career.
He also said he was shocked by the smell of human decomposition from a small sample of air taken from the boot of Anthony's car, and said it was 'extremely, overwhelmingly strong'.
When he opened the bottle, he said: 'I jumped back a foot or two. It was shocking that strong of an odour could be in that little can.'
Dr Vass, a key witness for the state, was the latest expert to give evidence at the sensational trial of 25-year-old Casey Anthony, who is accused of murdering her two-year-old daughter, Caylee.
He said chloroform can be a natural by-product of decomposition, but he told the court it would not produce the levels found in Anthony's 1998 Pontiac Sunfire. He said: 'The chloroform was shockingly high, unusually high.'
He said a stain on a section of carpet in the boot tested positive for the compound at a vastly greater concentration than could be attributed to natural processes.
As a bodily by-product, chloroform is generally measured in parts-per-trillion units. In Anthony’s car, he said, it registered levels quantified in parts-per-million.
'We were shocked. I have never seen chloroform in that level in environmental samples... I never have in 20 years of doing this,' Dr Vass said.
He said almost all the compounds present in the early stages of human decomposition were detected in the boot of Anthony's car, including traces of buteric acid, the first compound released by a body when it begins to break down after death.
On trial: Casey Anthony listens today as a forensic expert describes the 'shockingly high' levels of chloroform found in her car. The 25-year-old is on trial for allegedly murdering her two-year-old daughter, Caylee
He said scrapings taken from the vehicle’s wheel well showed up acetic acid, which was of interest not only because it results naturally from the process of decay 'but also because it’s a by-product of manufactured chloroform.'
An air sample taken from the boot and stored in a bottle also bore the stench of human death, said Dr Vass, who has worked for two decades at a University of Tennessee facility nicknamed the Body Farm, where human corpses are left to the elements to allow scientists to study the process of decay.
Testifying for the prosecution, Dr Vass said: 'The odour was extremely overwhelming and I was shocked that that little itty-bitty can could have such a strong odour. I recognised it as a human decomposition odour.'
He said human decomposition has a specific smell. He said: 'Animals can have a more musky scent. Domesticated animals like a pig have a much sweeter scent.'
Dr Vass has pioneered a new technique for detecting human decomposition from air samples, which he detailed for jurors.
But lead defence attorney Jose Baez objected to Dr Vass's testimony throughout the session, attacking his methodology and his credentials while the jury was sent out. His objections were denied.
He had previously tried to exclude the air tests from the carpet sample, but he was overruled by the judge. It's the first time the tests have been admitted as evidence in a U.S. trial.
On Saturday Karen Korsberg Lowe, an FBI forensic expert, said a hair removed from the trunk of Casey Anthony's car is consistent with hair from a dead body.
She said the light-brown, nine-inch-long hair was similar to one pulled from Caylee's brush and was not similar to a hair sample from her mother.
Ms Lowe also said the hair showed characteristics consistent with decomposition.
Anthony's daughter, Caylee, was a few weeks short of her third birthday when her grandmother, Cindy Anthony, reported her missing on July 15, 2008. 
The little girl's skeletal remains were found in a swamp close to the family home five months later.
Prosecutors are seeking the death penalty, alleging that Anthony killed Caylee with duct tape sealed tight over her nose and mouth then discarded her body in a swamp, freeing her up to go partying with friends and living 'the good life'.
Since June 16 that year, the child’s mother had insisted that Caylee was being looked after by a babysitter or was with friends.
But her defence attorney, Mr Baez, revealed in court last week  the babysitter and others were simply 'imaginary friends' and said his client had lied.
Once Anthony’s mother called in police to investigate the child’s whereabouts, Anthony made up more lies by then claiming that the nanny had kidnapped her, Mr Baez revealed.
He claimed Caylee drowned accidentally in the family swimming pool on June 16, but  Anthony covered it up at the behest of her father George, for fear that she could be branded negligent and sent to jail.
She complied, Mr Baez claimed, because she had been conditioned to obey her father since he began sexually molesting her at the age of eight.
Innocent: Two-year-old Caylee Anthony, whose skeletal remains were found in a swamp not far from her mother's house, five months after she went missing in July 2008
Innocent: Two-year-old Caylee Anthony, whose skeletal remains were found in a swamp not far from her mother's house, five months after she went missing in July 2008

Mr Anthony broke down in court during the first week of the trial as he denied the allegations. 'When I heard that ... it hurt really badly,' he said.
Legal experts say Anthony’s defence team face an uphill battle to prove her new version of events.
As well as showing she lied over her daughter’s disappearance, they have also aired audio and video tapes of jail conversations Anthony had with her parents in the days after her arrest.
They show her swinging between telling them lovingly that they are the best grandparents in the world, to her snarling aggressively at her mother for having called in police.
Throughout the conversations, she still maintained a nanny called Zanny had taken her child, despite knowing that Caylee was actually dead.
The little girl’s body was found in a swamp close to the family’s Orlando home in December 2008. The court has heard repeated evidence from witnesses, however, that Anthony was a loving and caring mother and that her daughter 'lit up' whenever she was in her presence.
Kendall Coffey, a former federal attorney for the Southern District of Florida, believes Anthony’s attorneys could have used that to bolster their argument that Caylee died accidentally.
But he says they may have blundered by introducing the claim about her father being an abuser who ordered her to keep it quiet and disposed of the body.
He said: 'Given all the question marks about this case and the lack of strong motive evidence for Casey Anthony to kill her own child, there might have been a defence ability to pause at accidental death.
'But what happened is that in the opening, the defence went too far, raised other sensational allegations that they don’t seem to have any sensational evidence to back up.'
Outburst: Casey Anthony smiled broadly and began giggling last week, covering her mouth with her hand as she waited for the afternoon session to begin on Thursday
Outburst: Casey Anthony smiled broadly and began giggling last week, covering her mouth with her hand as she waited for the afternoon session to begin on Thursday

He said: 'They might not have any choice but to put Casey Anthony on the stand. And given the clear evidence that she is a compulsive liar, that is the worst kind of choice any defence lawyer would have to make.'
As she watched the trial in the courtoom last week Thursday Anthony could be seen laughing. As she waited for the afternoon session to begin she smiled broadly, at one point trying to cover up her giggles with her hand.
Just two hours earlier jurors had heard dramatic tape recordings of detectives telling Anthony that she risked being judged as a 'cold-blooded, callous monster' after she lied to them over her daughter’s disappearance.
Anthony has pleaded not guilty to first-degree murder, and she faces the death penalty if convicted.
The trial continues.