06/06/2011 at 03:10 PM EDT
When Arpad Vass opened a canister containing air from Casey Anthony's car trunk, the forensic scientist recalls that he "jumped back a foot or two."
"It was shocking that strong of an odor could be in that little can," Vass testified Monday in the Orlando trial of the woman accused of murdering
her 2-year-old daughter, Caylee.
The prosecution witness is a senior research scientist at the Oak Ridge National Laboratory in Tennessee. He also does research at the "Body Farm" at the University of Tennessee in Knoxville, which is dedicated to the grim study of human decomposition.
Researchers tested chemical compounds evaporated from a piece of carpet recovered from the trunk of Anthony's Pontiac, where authorities suggest Anthony had stashed Caylee's body after the child disappeared
Several witnesses have recalled the foul smell.
Also recovered from the trunk was a strand of hair
that another expert says was similar to one of Caylee's.
Prosecutor Jeff Ashton asked if Vass believed there was a body in the trunk.
"I can find no other plausible explanation to explain all the results that we found," Vass said.
Vass had explained that he picked up the scent of chloroform, which comes with decomposition.
"The chloroform was shockingly high," he says – higher than any levels he had seen in 20 years of experience.
The defense frequently objected during his testimony about the study of air samples, a novel area in the law. Until the Anthony trial, no court has admitted air sample tests in a criminal case, according to experts.