Albert Ogletree, a food handler with Forte Food Service, was working in the cafeteria at Cantor Fitzgerald in the north tower of the World Trade Center when a hijacked jetliner careered into the skyscraper. He is one of the 2,983 people killed in the terrorist attacks of Sept. 11, 2001, and Feb. 26, 1993, when the trade center was bombed.

He is also one of only 10 victims whose portraits are not in the vast gallery at the National September 11 Memorial Museum, on the trade center site in Lower Manhattan. Museum officials have tried for years, without luck, to find someone who can furnish a picture of Mr. Ogletree — on vacation, perhaps; under a mortar board at graduation; beaming with happiness at his wedding; or hunched over a sketch pad drawing cars, something he loved to do.

Faces have defined the events of Sept. 11 since the earliest hours. On lampposts, bulletin boards and hospital walls, “Missing” posters beseeched passers-by to recall whether they had seen this face or that. Faces filled the pages of The New York Times and other publications and websites. Portraits were carried, facing the public, by survivors at memorial services and protest gatherings.

The museum’s goal is simple and increasingly challenging: to gather every face and weave it into the overwhelming tapestry of grief, loss, life and joy on display in the memorial gallery.