A 19th-century unsolved murder is probed in an analysis that makes a good run at being both solidly academic and convincingly mysterious but comes up wanting on both counts. In July 1841, only days after she disappeared, Mary Rogers, known as the ``Beautiful Cigar Girl'' for her work in a tobacconist's shop, was found floating in the Hudson River. Rogers's deathvariously attributed to strangulation (by the Hoboken coroner), drowning (by the New York City coroner), and an unsuccessful abortion (in a witness's deathbed confession)captured public imagination and provided raw material for dramatic renditions ranging from accounts in the penny press to openly fictionalized versions, including Edgar Allen Poe's ``The Mystery of Marie Rogàt.'' Srebnick (History/Montclair State Univ.), who uses the death to explore ``the historical place of women in . . . [that period's] economic and social transformations,'' is particularly interested in how sensational 19th-century accounts portrayed Rogers as either a chaste victim of urban toughs or, conversely, the very embodiment of danger (as an unmarried, sexually active woman). Not unlike the texts she critiques, Srebnick makes Rogers into the person she wants her to be: a member of the historically significant Mather family and a woman whose identity is ``emblematic'' of some important social changes. Where Srebnick might lose casual readers is when she detours into background that isn't always delivered with the intensity of the murder case. She might irk other readers in making questionable conjectural leaps and in not reconciling some details, as when she says that there was little violent death in New York City but also that it was ``not unusual'' for corpses to be found in local waters. Also, Srebnick uses her facts selectively, ignoring some that don't contribute to her greater purpose. A reminder that the past is unknowable and that history is whatever historians say it is.