While investigators believed they were linked before, they have determined that the letters that smoked and popped when opened were manufactured in the same manner, Richard McFeely, special agent in charge of the Baltimore field office, said Tuesday. Because the message inside the first two letters got out, McFeely said there were concerns that the third letter found a day later might be a copycat.
Fingerprint and fiber analysis is expected soon, McFeely said.
On July 7, a suspicious package addressed to Secretary of the Department of Homeland Security Janet Napolitano ignited at the facility in the 3300 block of V Street NE. The piece of mail flashed, popped, ignited, smoked and quickly went out, police said. No one was injured.
The previous day, two similar pieces of mail flared up at state government buildings in Maryland, causing minor injuries. A package addressed to Gov. Martin O'Malley at the Jeffrey Building in downtown Annapolis -- where mail for the governor is screened -- included a note reading, "Report suspicious activity. Total [expletive]. You have created your own self-fulfilling prophecy." The second package, addressed to Maryland Department of Transportation Secretary Beverly Swaim-Staley, ignited at the Harry Hughes Department of Transportation Building in Hanover.
Investigators are following more than 100 leads in the case, McFeely said, and a separate "red cell" team of investigators is exploring what could have motivated the sender.