As an aficionado of the Rosenberg case, I greatly enjoyed Sam Roberts's new book, The Brother: The Untold Story of Atomic Spy David Greenglass and How He Sent His Sister, Ethel Rosenberg, to the Electric Chair. As a historian, I was intrigued by how he chose to tell his story and document his research. Others might have structured the book differently, but perhaps less compellingly.

The Brother is the latest word on the infamous trial of Julius and Ethel Rosenberg, who were convicted in 1951 of conspiracy to commit espionage. As is well known, the U.S. government put the Rosenbergs to death by electric chair in 1953 for supposedly passing secrets about the atomic bomb to the Soviet Union during World War II. The couple left two young sons, Robert and Michael, who were raised by another couple, Abel and Anne Meeropol.

The Rosenberg case has sparked a lively historical debate focusing largely on the supposed guilt of the defendants. Among the players were the two Rosenberg children, Robert and Michael Meeropol, whose 1976 book, We Are Your Sons, memorialized their parents' deaths and argued that they were innocent. Also weighing in was the novelist E.L. Doctorow, whose thinly fictionalized The Book of Daniel was a sympathetic portrait of the Rosenbergs.

But it was two other books, Invitation to an Inquest by Walter and Miriam Schneir, and The Rosenberg File, by Ronald Radosh and Joyce Milton, that produced the most intense controversy. The Schneirs had originally published their book in 1965 but produced an updated edition in 1983. As its title implied, Invitation to an Inquest was an impassioned account arguing that the Rosenbergs were innocent, wrongly sent to death by a Cold War kangaroo court. In contrast, Radosh and Milton, having obtained FBI files on the Rosenberg case through a Freedom of Information Act request, argued the opposite in their 1983 book: Julius Rosenberg, for sure, had been passed materials about the atomic bomb to the Soviet Union. Ethel Rosenberg, the authors argued, was not clearly involved but had been unwilling to testify against her husband or"name names." While Radosh and Milton objected strongly to the death sentence, they felt confident that the charges had considerable basis in fact.

The debate between the Schneirs and Radosh and Milton culminated in a debate, held at New York City's Town Hall in October 1983. At the event, the impassioned authors joined impassioned audience members in revisiting not only the Rosenberg case but the divisions in the Left during the Cold War years. Little was resolved at this event and the controversy quieted down for some time.

What nearly everyone agreed upon was the role played by Ethel Rosenberg's brother, David Greenglass, in enabling the prosecution to convict the Rosenbergs. Greenglass and his wife, Ruth, testified that Julius had ensnared them in a Soviet spy ring, leading David Greenglass, who was employed at the Manhattan Project, to pass along secrets regarding the soon-to-be-built Atomic Bomb. Ethel, the Greenglasses testified, had known of Julius' activities and had helped to type out messages that were being transmitted. For his cooperation, David Greenglass was sentenced to only fifteen years in prison, of which he served less than ten. As Roberts, a reporter for the New York Times, notes, Greenglass has become a sort of cultural icon for a relative willing to testify against his own family members to save himself.

But Greenglass has never spoken on the record about the Rosenberg trial. After serving his prison term, he assumed a new identity and simply disappeared. Roberts, who had attended part of the trial as a child, became obsessed with finding Greenglass and getting him to talk. Finally, in 1990, Roberts found his target, cornering him in his Queens, New York driveway. And while it took Roberts six years, he finally got Greenglass to speak, in exchange for a portion of the royalties from The Brother. The basis for Roberts's conclusions include Greenglass's recent account of events; newly available materials from the Venona project, an American spy operation that decoded World War II Soviet intelligence; and the testimony of Alexander Feklisov, the Soviet agent who worked with Julius Rosenberg.

What is so interesting about The Brother from the perspective of a historian, is how little of the historiographic debate about the Rosenberg case appears in the early portion of Roberts's book. Eschewing the tendency of most historians to lay out others' arguments and then indicate how the current work will fill gaps in knowledge, Roberts prefers to simply retell the story of the Rosenberg spy case by himself.

To be sure, he builds on the work of past writers, but his references are extremely spotty. Roberts relies on the increasingly common practice of leaving out suprascript numbers from his text. Rather, the reference section at the end of the book contains boldfaced page numbers and explanations of some of the quotations and other assertions that are found on the book's pages. But many pages have no citations at all. As a result, the reader seeking information about a background source is more than likely to be disappointed. Unless one is familiar with the entire Rosenberg ouevre, it appears, Roberts's paper trail will remain rather opaque. While the decision not to laden the text with multiple citations surely makes the book more readable, it limits its use as a reference by future historians.

Roberts's stylistic choices also limit his inclination to comment on the historiographic significance of his work. He does describe in the book's concluding chapters how his account corroborates many of the conclusions of Radosh and Milton. Roberts also builds on this earlier work by getting Greenglass to admit that he was not certain that Ethel Rosenberg had typed messages for Julius--the supposed activity that may have led to her conviction. Yet Roberts reflects little on the rather remarkable ways in which the story of the Rosenbergs has previously been written and rewritten.

What seems so fascinating, in retrospect, is how incomplete the once"definitive" book by the Schneirs actually was. Lacking information from the FBI, Soviet archives and Greenglass himself, the Schneir book becomes a cautionary tale about the dangers of writing"incomplete" history. It is, of course, also a story of how the emotional and political orientation of historians can influence their conclusions. The Schneirs amassed an enormous amount of evidence showing that the Rosenbergs had been railroaded, but we now know that this material only provided one side of the story. The Rosenberg trial, the Schneirs had written,"was a product of its times, displaying in microcosm many of the prevalent sociopolitical assumptions and preoccupations of the day." The same could be said for their book and We Are Your Sons, both of which were informed by the radical politics of the 1960s and 1970s.

Of course, we should not label Roberts's account the last word. Just like other historical sources, the material obtained from Venona and Feklisov should not simply be taken at face value. Nor should we necessarily trust Greenglass, whose history of telling self-serving lies permeates Roberts's book.

But historiography is not simply a process in which authors provide equally valid, competing accounts. When well-researched history gets done, we do progressively learn more about what"actually" happened. And that is occurring in the Rosenberg case. Given the work of Radosh and Milton, Roberts, and another new book written by Feklisov himself, it is clear that Julius was guilty of passing atomic secrets to the Soviets. And Ethel, while involved more peripherally, knew of her husband's activities and chose to remain silent, thus condemning herself to the electric chair.

None of the proceeding discussion is meant to exculpate those involved in putting the Rosenbergs to death. As Roberts, the Schneirs and others have documented, trial judge Irving Kaufman, caught up in Cold War fervor and potentially nervous about letting fellow Jews off the hook, gave far too much support to the prosecution and greatly exaggerated the importance of the material that was passed along to the Soviets. And the decisions of Kaufman, the Supreme Court, and ultimately President Dwight Eisenhower to support the death penalty spoke less to the crimes committed than the poisonous political atmosphere of the Cold War. In a new era of crackdowns on civil liberties in the name of stopping terrorism, it is perhaps this lesson of the Rosenberg case that we should heed most closely.