Most prolific book thief

The most prolific book thief was Stephen Blumberg (USA), who stole at least 23,600 rare books (weighing a total of 19 tonnes) from 268 different libraries across North America between the 1970s and 1990. Blumberg was turned in by a former accomplice, Kenneth Rhodes, in 1990 and convicted in July 1991 on four counts of possessing and transporting stolen property.

Blumberg, who had been diagnosed with a schizoid personality disorder at the age of 15, was driven by a belief that modern society had lost its ability to appreciate beauty and quality, and that it was his duty to protect the artefacts of earlier, more refined ages from indifferent modern caretakers. He had particular enmity for librarians, who he saw as careless and neglectful.

Blumberg lived a largely nomadic life, acquiring books and pieces of architectural salvage (he was also an expert on 19th-century stained glass) on months-long cross-country road trips. He would keep the books, but sell the architectural salvage and that, along with his $72,000-per-year trust fund, provided the income he needed to pay his expenses. Despite his significant financial resources, Blumberg never paid for books, instead sinking considerable time and resources into his library heists.

His typical methodology was to enter a library during opening hours, often using forged or stolen credentials, to get a sense of the layout and where the valuable material was stored. On later trips he would endeavour to acquire a staff pass or set of keys, then return at night to take what he wanted. Blumberg was short and extremely slim, capable of squeezing over security cages or up dumbwaiter shafts.

Blumberg's thefts went largely unnoticed for most of his criminal career, and only one person – University of Washington campus police officer Stephen Huntsberry – seems to have suspected there was a serial book thief at large in the United States. Huntsberry got on the trail of Blumberg after a man identified as "Matt McGue" (a Blumberg alias) was seen acting suspiciously around his university's library at the time of a number of thefts. Ultimately, however, it was not detective work, but the actions of a former accomplice and friend, Kenneth Rhodes, that led to Blumberg's arrest. Rhodes collected details of Blumberg's thefts and the extent of his stolen library before going, unsolicited, to the FBI. He sold them this information, and a promise to testify at the trial, for $56,000.

Blumberg's closest rival is likely the 19th century academic Guglielmo Libri, who stole a vast hoard of manuscripts and rare books during his tenure as Chief Inspector of French Libraries from 1841 to 1848. His focus as a thief appears to have been manuscripts and handwritten items such as letters, however, rather than books. His personal Library was estimated (by the man himself) at around 30,000 volumes in 1851, but a large portion of this was probably legitimately purchased and the numbers likely inflated.