The items were found missing in 2001, but at the time staff believed they may have been placed on the wrong shelves. They carried out extensive searches of the library – which houses some 10 million books, maps, manuscripts and other objects – but in October 2020 they were reported stolen from the Cambridgeshire police station. The police force launched an investigation and notified Interpol, with the university making a global appeal for information. Nearly a year and a half later, the notebooks – one of which contains Darwin’s 1837 basic sketch of the Tree of Life – were returned anonymously. Notebooks were found to be missing in 2001. Photo: Cambridge University Library / PA They were left in the pink gift bag on the floor of a public library area outside the librarian’s office, on the fourth floor of the 17-story building, on March 9th. The area is not covered by CCTV. The manuscripts are said to have been in good condition and without obvious signs of significant handling or damage that they suffered over the years from their disappearance. The two notebooks were wrapped with foil inside their file box. A simple coffee envelope had the message “Librarian / Happy Easter / X” printed on it. The notebooks were left in a pink gift bag outside the librarian’s office. Photo: Cambridge University Library / PA The police investigation into the disappearance and subsequent return of the notebooks is ongoing. Dr. Jessica Gardner, who became director of library services in 2017 and reported the notebooks as stolen to police, described her joy at their return as “huge.” “My sense of relief for the safe return of notebooks is deep and almost impossible to adequately express,” he said. “I, along with so many others around the world, was saddened to learn of their loss. “The only goal of our public appeal was to return the manuscripts safely to our custody and I am glad that I had such a successful result in such a short time. “Notebooks can now take their rightful place next to the rest of the Darwin Archive in Cambridge, at the heart of the nation’s cultural and scientific heritage, along with the archives of Sir Isaac Newton and Professor Stephen Hawking.” Although there is no closed-circuit television in the area where the manuscripts were returned, Gardner said the building’s entrances and exits were covered, as were targeted areas such as powerful rooms and specialized reading rooms. He said the available footage had been handed over to police, adding: “It’s really a mystery. We do not know how and we do not know who. “ The notebooks had been removed from storage to be photographed in the library’s photographic unit, where the work was completed in November 2000. During a follow-up in January 2001, the small blue box containing the notebooks had not been returned to its place. Gardner said the library building had been “significantly transformed” since then, with card and pin access to safe areas, an on-site security team, powerful high-security rooms and additional CCTV. He added that “more root and industry revisions of all our security protocols will be made – to make sure we minimize any future risk as humanely as possible.” Professor Stephen J Toope, vice-chancellor of the University of Cambridge, said he was “incredibly happy to hear about the safe return of the notebooks to their legal home”. “Objects like these are vital to our understanding not only of the history of science but also of the history of humanity,” he said. The notebooks will be on public display from July, as part of the library’s Darwin in Conversation exhibition. A Cambridgeshire police spokesman said: “Our investigation remains open and we are following some lines of inquiry. We also renew our appeal for anyone who has information about the case to contact us. ”