(CNN) -- Forensic testing on a carpet sample from Casey Anthony's trunk showed the presence of chloroform at a level that was "shockingly high," a scientist testified Monday in her capital murder trial.
The level was far beyond what normally would be seen in environmental samples, said Arpad Vass, a senior research scientist at Tennessee's Oak Ridge National Laboratory, and higher than any he has seen in his nearly two decades of forensic study.
"The chloroform was shockingly high, unusually high," Vass said. The same testing done on a "control sample" of carpet from a similar make and model vehicle also showed chloroform, but the level was much lower, he testified.
Laser-based testing also seemed to indicate that decomposition had occurred in the trunk, as it showed high levels of inorganic elements such as calcium. Such inorganic elements are consistent with a decomposing body, Vass testified in an Orlando, Florida, courtroom.
Casey Anthony, 25, faces seven counts in the death of her 2-year-old daughter Caylee, including first-degree murder, aggravated child abuse and misleading investigators. If convicted, she could face the death penalty.
Caylee was last reported seen by her family on June 16, 2008, but no one alerted police until July 15, when the girl's grandmother, Casey Anthony's mother, tracked Anthony down and demanded answers.
Prosecutors allege Anthony used chloroform on her daughter and suffocated her by putting duct tape over the little girl's mouth and nose. They allege Anthony put her daughter's body in the trunk of her car before disposing of it. Caylee's skeletal remains were found in December 2008, less than a mile from the home of Anthony's parents.
Anthony has pleaded not guilty and denied having anything to do with her daughter's death. The Orlando woman's attorneys argue Caylee drowned in the family pool on June 16, 2008. They say Anthony and her father panicked and covered up the death. George Anthony denied the claim during his testimony.
Vass' testimony was frequently punctuated by objections from Anthony's defense attorneys. Nearly all of them were overruled by Orange County Chief Judge Belvin Perry Jr., but the judge at one point allowed defense attorney Jose Baez to question Vass about the testing outside the presence of the jury.
Vass gave jurors in the trial a crash course in the stages of human decomposition and explained his nearly 20 years of study, some of which was done at "The Body Farm," the anthropological research facility located near the University of Tennessee campus.
Some of his research, Vass explained in his highly technical testimony, has concerned the odors emitted by human decomposition.
Vass said he was contacted by Orange County Sheriff's Detective Yuri Melich and asked to examine evidence in the Anthony case, and requested air samples from various points in Casey Anthony's car.
A crime scene investigator, the operator of a towing company and members of Anthony's family all have testified they smelled a bad odor coming from Anthony's car after it was found abandoned in a parking lot on June 27, 2008, and then towed four days later. The prosecution maintains the odor in the car was that of human decomposition, and says cadaver dogs also alerted to it.
Vass testified the odor in the air samples he received was "extremely overwhelming" and he identified it as human decomposition. Tests on scrapings from the wheel well of Anthony's car showed the presence of acetic acid, he testified. The substance is "a byproduct of human decomposition," he said, as well as a byproduct of the manufacture of chloroform.
On Saturday, an FBI evidence analyst testified that a single hair found in the trunk of Anthony's car was similar to that of Caylee and showed evidence of decomposition.
But defense attorney Jose Baez attacked the findings by FBI trace evidence examiner Karen Lowe as unreliable.
Testimony about the hair marked a departure from the dramatic testimony and evidence offered in the first nine days of the trial, in which friends and acquaintances contradicted Anthony's claims that she was frantically searching for her daughter during the month she was missing.
Instead, she was staying with her boyfriend, spending time in Orlando with numerous friends, attending parties, going shopping and hitting nightclubs, including participating in a "hot body" contest, according to testimony in the case.
Her former boyfriend, friends and acquaintances have all testified that she did not mention her daughter being missing during that time and that they noticed nothing different about her demeanor.
In dry, scientific terms, Lowe testified Saturday how a 9-inch piece of hair sent to the FBI lab in Quantico, Virginia, appeared similar to a piece of hair recovered from a brush belonging to the girl.
But she said hair analysis is not as precise as DNA analysis, so she could not say with absolute certainty that the hair belonged to Caylee.
The hair had a dark band that Lowe testified has only been seen in hairs remaining in the scalp of a decomposing body.
In cross-examination, Baez questioned the validity of Lowe's testimony, first asking if there was any way to prove how the hair got into the trunk.
"I couldn't say how the hair got there," Lowe said. "It's consistent with transfer or contact of some sort, but I don't know from whom."
She also testified under questioning from Baez that while the hair is clearly not Casey Anthony's, it could belong to any other light-haired relative on her mother's side of the family. The kind of DNA testing authorities were able to perform on the sample reveals DNA passed down only through maternal lines.
Lowe also testified there are no standards for identifying the bands and that such decisions are based on her opinion and that of a fellow investigator.
Baez also questioned Lowe's experience, saying she had failed a 2000 proficiency test and that she has never before testified on hair banding.
In addition, he questioned the entire premise of hair analysis, citing a 2009 National Academies of Science report that broadly questioned the use of microscopic hair analysis and other forensic science results in criminal cases.
Lowe said she agreed with the report's findings -- that hair can't uniquely identify an individual and that it's important to send samples for DNA analysis, which she said she did in the Anthony case. Lowe, who is not a DNA expert, has not testified about the findings of the those tests.
The hair in question was recovered after Anthony's car was picked up from her family's home, after it had been abandoned in a parking lot, towed to an impound lot and then driven back to the family home two weeks later by Anthony's father.
According to testimony, Anthony asked her boyfriend to pick her up from the parking lot on June 27, saying the car had run out of gas. She also told a friend that she believed an animal carcass was lodged in her car's frame.
The car was towed to an impound lot on June 30, 2008, where a manager said he smelled the odor of decomposition.
Also on Saturday, Orange County crime scene investigator Mike Vincent told jurors about collecting air samples from inside Anthony's car.
Baez questioned whether the air inside the trunk on August 29, 2008, when it was tested, was the same as that in the car when it was recovered in July.
He also sought to raise a question whether a trash bag found in the car when it was recovered might have been the source of the smell. Vincent also sampled air from the inside of that bag. The contents of the bag were dry when Vincent tested the air inside, he testified. The trash might have smelled different when, and if, it was wet, Vincent said under questioning from Baez.
Before prosecutors began presenting scientific evidence in the case on Friday, jurors watched recordings of jailhouse visits between Anthony and her parents.
In one conversation played Friday, Anthony scoffed at a media report her mother brought up speculating that Caylee had drowned in the family swimming pool.
"Surprise, surprise," Anthony said of the rumor, which is now the primary defense theory.
Anthony's defense team explains her behavior in the weeks following Caylee's death by saying she had been sexually abused by her father and had been taught to conceal her pain. George Anthony has denied abusing his daughter.
The excuses
Testimony earlier in the trial in Orlando revealed that Anthony lied to her parents and avoided them for 31 days in the summer of 2008 while Caylee was supposedly missing.
During the second week of the trial, jurors learned more about what Anthony told her parents during that time and what she was actually doing.
From the witness stand Tuesday, Anthony's mother described heated confrontations with her daughter on July 15, 2008, after she learned Anthony had been lying about her whereabouts for a month.
The stories began with Anthony saying she was having a sleepover with a nanny named Zenaida "Zanny" Gonzalez. Then, Anthony said she was out of town on a work trip to Tampa, Florida.
By the fourth week, Anthony's story was that she was out of town visiting an old boyfriend named Jeffrey Michael Hopkins.
Cindy Anthony caught her daughter in her lies by discovering she was, in fact, in Orlando with a different boyfriend. By the time her mother called 911 to report Caylee missing, Anthony had a new story.
"I know who has her. She's been my nanny for about a year-and-a-half, almost two years," Anthony told the operator in the July 15, 2008, call, which jurors heard Tuesday.
When asked by the operator why she waited so long to report her daughter missing, Anthony replied, "I have been looking for her and have gone through other resources to try to find her, which was stupid."
The characters
In the following days, Gonzalez's alleged role would expand from an occasionally-mentioned nanny to a central character in Caylee's disappearance.
When initially questioned by Orange County Detective Yuri Melich on July 16, 2008, about Gonzalez, Anthony provided a description of her without hesitation. That interview was played Wednesday.
Anthony said she'd known Gonzalez for four years after they met working together at Universal Studios. She provided a physical description of Gonzalez, her address, even her mother's name.
Other characters were also fleshed out. Hopkins, a former Universal Studios co-worker, according to Anthony, lived in Jacksonville and had a son named Zachary who played with Caylee.
And then there was Juliette Lewis, another co-worker at Universal, who now lived in New York, Anthony said. She also had a daughter Caylee's age.
Anthony claimed she called Lewis and Hopkins when she realized Caylee was missing. But prosecutors claim Anthony was not looking for her daughter in the month she was missing.
Instead, she was staying with her boyfriend, spending time in Orlando with friends, attending parties, going shopping and hitting nightclubs, according to testimony from friends, her former boyfriend, and acquaintances, who also said that she did not mention her daughter being missing during that time.
Anthony's frustration level with her parents, particularly her mother, was rising around the time Caylee disappeared, friend Amy Huizenga testified Tuesday.
"I remember she told me her mom had told her she was an unfit mother. She was extremely upset about that," Huizenga said.
But Anthony also was agitated at her mother because she had to cancel plans "fairly frequently" when no one was available to watch her daughter, Huizenga testified.
In late June, Huizenga said, Anthony told her that she was keeping Caylee away from her parents, as they were having marital problems and were considering divorce, and "she wanted to keep Caylee out of the drama."
'Fessing up
On Thursday, Melich described the day Anthony was finally forced to admit her lies, at least in part. On July 16, 2008, Melich worked with Universal Studios to scour the employee database.
Anthony was in the database, but she hadn't been affiliated with Universal for years. Melich also found no record of Gonzalez or Lewis.
A Jeffrey Hopkins was found, but never worked for the company at the same time as Anthony. Gonzalez's supposed apartment had also been found vacant.
Anthony voluntarily met Melich at Universal Studios to discuss the matter. Melich testified Thursday that he watched Anthony try to enter the park without a badge, then attempted to lead him to her office before being forced to admit she didn't have one.
"I can tell you just for certainty everything you've told me so far has been a lie," Melich said in a recorded interview played for the jury on Thursday.
"I've gone to every address that you've told me. I've looked up every name, I've talked to every person that you wanted me to talk or try to. And found out all these names you're giving me are people that either never worked here or been fired a long time ago, OK?"
Anthony conceded she didn't work at Universal and that the people she had described as her co-workers did not exist. Yet she continued to blame Gonzalez for the disappearance of her child.
Cindy Anthony said her daughter had been telling her about Gonzalez along with numerous other people -- a boyfriend, a co-worker and a man named Eric Baker, whom she believed to be Caylee's father -- for years before Caylee went missing.
At the time, she said, she never had a reason to believe those people were fictitious. "I just found out they were imaginary people," she testified.
A Zenaida Gonzalez was later found, but she had no affiliation with Anthony aside from having filled out a guest card at the Orlando apartment complex where Anthony claimed the nanny lived.
The apartment where Anthony said Gonzalez lived was found to be vacant, and there was no record of Gonzalez in the Universal Studios employee database.
Anthony has denied killing her daughter. She faces the death penalty if convicted.
CNN's Ashley Hayes contributed to this report.
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