New and more sophisticated tests have turned up trace amounts of anthrax at a postal distribution center that sorts mail for a town where a 94-year-old woman died of the disease.

But baffled investigators still have no evidence that Ottilie Lundgren, who died Nov. 21 in her Oxford home, contracted inhalation anthrax from the mail.

The anthrax was found on four mail-sorting machines at the Southern Connecticut Processing & Distribution Center in Wallingford, where workers handle about 3 million pieces of mail daily headed for New Haven, Middlesex and New London counties.

The center had been tested three times before and no signs of anthrax were found. But on Nov. 28, workers used a special vacuum with a filter designed to trap minute particles, and scientists found trace amounts of the bacteria, said Mike Groutt, a spokesman for the federal Centers for Disease Control and Prevention.

"The vacuum is designed to get down to where spores might be in the cracks and crevices," Groutt said.

The machines most likely were contaminated when an anthrax-tainted letter destined for an address in Seymour, a few miles from Lundgren's home, passed through the plant on Oct. 11, said Jon Steele, vice president of the Postal Service's Northeast Area Operations.

On Friday, officials announced the discovery of that letter, which contained a single spore of anthrax. So far, investigators have not found any link between Lundgren and the letter.

"This (latest) finding is not a complete surprise," said Steele. "The public should not be panicked by trace elements occurring nearly 60 days ago."

The sorting machines will be decontaminated, a process that could take several days, Steele said. The center will remain open for business.

The facility was tested four times and a combined total of 389 samples were taken, he said. Five samples in the latest round of testing revealed anthrax, Steele said.

About 900 of the 1,200 postal employees at the plant are taking antibiotics as a precaution, said Christine Dugas, a spokeswoman for the U.S. Postal Service.

"This is a very small amount of anthrax," said Dr. Joxel Garcia, the state's commissioner of public health. "The people of Connecticut should not be concerned about opening their mail."

Meanwhile, health officials from New York were in Hartford on Sunday to compare notes about the anthrax deaths of Lundgren and Kathy Nguyen, a 61-year-old woman from New York City.

Nguyen died on Oct. 31, becoming New York's first case of inhalation anthrax. Like Lundgren, she was older, lived alone and spent a lot of time by herself.

Investigators have so far been unable to determine conclusively how either woman contracted the disease. The mail has been a focus of both investigations.

Officials from the CDC, the health departments of both states, the FBI, and the Postal Service met Sunday to discuss the cases, Groutt said.

Tests have so far turned up no trace of anthrax at either woman's home, or at Nguyen's workplace at Manhattan Eye, Ear and Throat Hospital. No sign of anthrax was found at the church, hair salon or other businesses Lundgren was known to visit.