Some things are better forgotten.

The danger posed by anthrax – and the fact that a killer, who has used the biological agent as a weapon, remains free – shouldn’t be.

We got a reminder of the 2001 anthrax horrors on Monday when traces of the substance were detected at a Pentagon mail facility. So far, no one has been diagnosed with anthrax poisoning. But the Centers for Disease Control and Prevention and the U.S. Postal Service are closely monitoring hospitals and testing other facilities in the Washington area. Antibiotics have been recommended for workers in several offices, just as a precaution.

All mail received by the Pentagon is irradiated, and subsequent tests were not positive for anthrax, but, as they say, it’s better to be safe than sorry.

The first signs that anthrax had been used as a weapon in the United States appeared in October 2001. Five people died in all, 17 became sick, thousands were prescribed precautionary antibiotics, mail service was obstructed in several cities, including Washington, D.C., and going to the mailbox became a test of grit for people from sea to shining sea. Even people in small, isolated towns reacted.

Still on alert, the University of Southern Maine reacted aggressively against a suspicious package received Monday at its Gorham campus. The package was a large envelope with a Gaza Strip return address. It had an incorrect address and excessive postage. The envelope was tested for explosives and chemicals and then sent to Augusta for more tests. There’s no apparent connection between the USM event and what’s going on in Washington. But it is a reminder of the heightened vigilance that remains a necessity for large institutions.

Despite the combined resources of the United States government, the anthrax killer from 2001 has not been brought to justice. There are doubts that he or she ever will. Federal Judge Reggie Walton has given the FBI until April 22 to solve the case. After that date, Walton says he likely will allow a lawsuit filed by Steven Hatfill to go forward. Hatfill is suing the FBI and former Attorney General John Ashcroft. Hatfill says his reputation was damaged after he was identified as “a person of interest” in the 2001 anthrax attacks.

A task force of federal law enforcement agents remains on the case, and we are hopeful for a breakthrough. The events earlier this week at the Pentagon and at USM are enough to bring the days of dangerously tainted mail back to mind.

Coordination has not gone smoothly, even though the federal, state and local authorities have had three-and-a-half years to prepare. According to The Washington Post, local fire departments and health officials were initially left out of the loop by the Defense Department.

People died when a biological weapon was used against them. We shouldn’t forget that, and we shouldn’t forget the lessons that were learned about coordinating responses and sharing information. On that front, USM appears to have done a better job than the feds.