By Barbara Liston
ORLANDO, Fla (Reuters) - A lawyer for accused child killer Casey Anthony on Monday attacked the new science of identifying human decomposition by a body's chemical vapors.
"This is the first time you've ever given this testimony in a court of law?" defense attorney Jose Baez asked Arpad Vass, a research scientist from the Oak Ridge National Laboratory in Tennessee.
Vass said yes, but maintained that chemical compounds in air and fiber samples taken from Casey's car trunk were consistent with decaying human remains.
"I can find no other plausible explanation other than that," Vass told jurors under questioning by prosecutors earlier in the day.
Casey Anthony, 25, is standing trial in Orlando, Florida for a first-degree murder charge stemming from the June 16, 2008 death of her 2-year-old daughter Caylee.
Prosecutors are seeking the death penalty. Monday marked the start of the third week of the trial.
Caylee was reported missing on July 15, 2008 by her grandmother, who hadn't seen the toddler in a month and smelled an odor she likened to a dead body in Casey's trunk.
Casey's defense team contends Caylee drowned in the Anthony family's backyard pool but no one reported her death. Casey initially told detectives that Caylee was kidnapped.
During a 5-month nationwide search for Caylee, cadaver dogs signaled that they smelled decomposition on her backyard playhouse, prosecutors said.
Air and carpet samples from the foul-smelling car trunk were sent to Vass, whose ground-breaking research focused on finding a way to locate bodies from the chemical signatures in their odor, much like a dog recognizes the smell.
Vass testified he has worked for 20 years in the Oak Ridge lab's outdoor body farm, where human remains are studied in various stages of decomposition. He said he has worked with 50 bodies from the time of death until they were skeletonized, plus hundreds of other bodies in various stages of decay.
Vass said his research determined the chemical compounds emitted by human remains at various stages of decomposition.
In the air analysis of the car trunk sample, Vass said he and other scientists detected 51 compounds including an unusual quantity of chloroform. Chloroform is released by decaying bodies, Vass testified.
"We were shocked. We had never seen chloroform at that level," he said.
In their opening statement, prosecutors told jurors someone had researched chloroform, once a popular anesthetic, on the Anthony family computer in the months before Caylee's death.
Vass testified the lab also conducted laser tests on a sample of the carpet from Casey's car trunk to look for inorganic elements such as calcium, sodium, magnesium, iron and carbon. Vass said calcium was found in the greatest quantity.
"They showed the inorganic elements associated with human decomposition were significantly elevated," Vass said.
Baez fought without success to ban Vass's testimony before trial, calling the science new and unreliable. The test results had never been used as evidence in a court before.
On Monday, the defense attorney sought to discredit Vass and his work. Baez challenged the adequacy of protocols in Vass's research and protection of samples from contamination.
He grilled Vass on whether a successful prosecution would benefit him financially.
Vass acknowledged he helped invent a tool, based on his research, that helps detectives find hidden graves, and that he might eventually receive royalties if the tool is manufactured.
Vass also agreed with Baez that mammals could produce the acids researchers found on a paper towel from a trash bag in the car trunk. The acids are a byproduct of the decomposition of fat.
But "it couldn't be caused by someone eating a hamburger and wiping their face," Vass said, adding that the quantity of acids found would require several pounds of raw and fatty meat loaded with the same type of bacteria found inside a body.
(Editing by Colleen Jenkins and Jerry Norton)