The federal government has agreed to pay $2.5 million to the widow and children of the first person killed in the anthrax letter attacks of 2001, settling a lawsuit claiming that the Army did not adequately secure its supply of the deadly pathogen. The settlement with the family of Robert Stevens, a tabloid photo editor in Florida, follows an eight-year legal battle that exposed slack rules and sloppy recordkeeping at the Armys biodefense laboratory at Fort Detrick, in Frederick, Md. As part of the agreement, Justice Department lawyers are seeking to have many documents that were uncovered in the litigation kept under court seal or destroyed. Mr. Stevenss widow, Maureen, filed suit against the government in 2003, as evidence accumulated that the anthrax powder in the lethal letters had come from an Army laboratory. Mr. Stevens, 62, died on Oct. 5, 2001, days after inhaling anthrax powder at work.