John Mark Tillman of Halifax, Nova Scotia, pleaded guilty to 40 charges, including fraud, theft and possession, the Canadian Broadcasting Corp. reported.
Police stumbled onto the case during a routine traffic stop in July 2012. An officer spotted a historic letter from British Gen. James Wolfe and a $1,500 check in Tillman's car. Detectives traced the letter to Killam Library at Dalhousie University, where it had been reported stolen.
Tillman, it turns out, was a regular at several university museums in Atlantic Canada over the years and took advantage of loose security at the academic libraries to make off with all manner of historic documents, some of which he resold and some he kept, police said.
Two of the more valuable thefts included a first edition of Charles Darwin's seminal "Origin of Species," stolen in 2009 and sold for $31,000, and a hand-written letter from George Washington to an associate in Halifax instructing the recipient to spy on British forces.
Tillman kept the Washington letter, which was reported stolen from Dalhousie and is estimated to be worth between $50,000 and $100,000.
Both prosecutors and Tillman's attorney agreed to a nine-year prison sentence minus one year for time served since his arrest.