One year, before he moved to New Jersey, he took his mother to New York. One year he took her to Washington for a tour of the White House. Some years, she would simply visit his apartment and cook. This year, for their annual vacation, Mary Keohane and her son, John, 41, were planning to meet in Florida on Saturday, Sept. 15.

He had loved the idea of travel since he was a boy building model airplanes and visiting his grandmother's house, which sat in the flight path of San Francisco International Airport. As an adult, Mr. Keohane — an energetic, good-humored yet quiet lawyer at the Zurich company, according to his sister, Darlene — liked to say he had visited everywhere except Antarctica.

Mary Keohane's bags were already packed when her phone rang in Northern California around 7 a.m. on Sept. 11. It was her son saying he had safely left 1 Liberty Plaza, where he worked, and met up three blocks away with his partner, Mike Lyons, who worked nearby.

Hearing a loud noise, Mr. Keohane told his mother that a third plane had hit a building. The connection was lost. The second tower was collapsing, spreading darkness through the streets — Mr. Keohane became separated from Mr. Lyons and was hit by debris. Weeks later, the Keohanes received a letter from a priest at a downtown church, saying he had found Mr. Keohane about two minutes later and performed last rites.