Connecticut anthrax probe winds down

OXFORD, Connecticut (CNN) -- Authorities are winding down their investigation into a 94-year-old New England woman's mysterious death from anthrax.

The best theory is that Ottilie Lundgren, who died November 21, contracted anthrax through a piece of mail cross-contaminated with a tainted letter, federal health officials said Tuesday.

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The widow's home was released as a crime scene Monday night after a final walk-though by the FBI and Connecticut State Police.

"Nothing was discovered, and it was concluded that no more evidence was to be found in the house," said Sgt. J. Paul Vance, a spokesman for the state police.

Despite dozens of environmental tests and searches, no traces of anthrax or suspect letters were found in Lundgren's home.

A trace amount of anthrax was found on an envelope of a letter sent to a home in a nearby community, backing the theory the mail played a role in the case. Vance said the Lundgren case remained "open and active."

Lisa Bull, a spokeswoman for the FBI in Connecticut, said the anthrax investigation remained active on several fronts.

"We are winding down the investigation that relates to Mrs. Lundgren's death, but we are continuing the national initiative that may in fact resolve the issues surrounding Mrs. Lundgren's death," Bull said.

"In Connecticut, we've exhausted all leads. However, if additional leads arrive, we will pursue them aggressively."

Sharon Hoskins, a spokeswoman for the Centers for Disease Control and Prevention in Atlanta, Georgia, said that although investigators have not been able to connect Lundgren to a specific piece of mail, cross-contamination remained the strongest explanation for how the widow came in contact with anthrax.

Michael Groutt, part of a 30-member CDC team in Connecticut for the investigation, said more than half the team had returned to Atlanta to examine the results collected in Connecticut.

Lundgren was one of 18 people with confirmed anthrax infections in the United States since contaminated letters began turning up in the mail in October. Five people died and authorities are still searching for a culprit or culprits.

Lundgren's death and that of 51-year-old New York City hospital worker Kathy Nguyen have proved perplexing because, unlike the other cases, they had no clear links to government or news media offices, targets of the tainted missives, and they were not affiliated with the Postal Service.