The labs in Amoco's Building 503 are empty, scrubbed clean and ripped apart.
"We even pulled out drain traps and sinks and then floors and tested for all types of chemicals," said safety manager Michael Wells.
Since 1989 Amoco has been on the hunt for a possible killer at its Chicago area research center, reports CBS News Correspondent Maggie Cooper.
"We want to understand if there's anything that's going on here that has caused an increase in cancer," Wells said.
The third floor of the 503 building has been sealed off since 1996, when researchers here expressed concern about working in these labs. So far, 7 Amoco employees have been diagnosed with a rare brain cancer. Five have died.
Amoco says it safeguarded the researchers who worked here daily with toxic chemicals. A multi-million dollar investigation has yet to turn up a clue to the cause of the cancer.
"There were many incidences that took place, such as accidental spills, that frightened me to no end," according to maintenance worker George Varney.
Varney thinks there is a connection. For 13 years he maintained the ventilation system in the Amoco complex. A few months ago he was diagnosed with a rare and fatal liver cancer.
"The long and the short of it is, unless we have a liver transplant, there is no cure," Varney said.
Varney's Attorney Robert Clifford claimed "The Amoco building unquestionably was operated in a fashion that was not environmentally safe."
George Varney repeatedly alerted superiors to his safety concerns. But Amoco denies the chemicals in the building were to blame for his liver cancer.
"To date researchers tell us that the only unusual pattern of cancer that has occurred on this site is the brain cancer," Wells said.
Varney is one of twenty who have sued.
Clifford said it was "highly unlikely" that Varney will live to see the results of the trial.
Even as the courts weigh the issue of liability, at Amoco the search for a killer continues.