Those notes, written into his calendar, are now part of the evidence to be used against him in his trial on 31 charges of fraud, breach of trust and bribery that got underway Monday.
Duffy pleaded not guilty and says he did nothing wrong. He says the Senate's rules for travel and living expenses are unclear, and that he was entitled to the reimbursement he claimed.
Some of the entries on his calendar provide insight into some big news stories. Others are likely to be of more interest to those who follow politics carefully, and still others are entirely mundane details like what Duffy had for dinner or what movie he watched with his wife, Heather.
The notes represent only Duffy's view of events.
Doug Finley cut out
Shortly after the May 2, 2011, election, Duffy writes that then MP Dean Del Mastro phoned him. The Peterborough, Ont., politician had just been re-elected and had previously served as a parliamentary secretary to the heritage minister.
"Dean Del Mastro calls re: cabinet shuffle - Have I heard anything?" Duffy noted in the calendar.
During the election campaign, Duffy wrote that Conservative Senator Doug Finley phoned him. Finley had been one of the primary architects of the Conservative Party's rise to power but played a reduced role during the 2011 election. It also seems the two discussed a story Sun Media planned to run about then Liberal Leader Michael Ignatieff.
"Doug Finlay [sic] calls re: Sun scoop upcoming on Ignatieff + Guy Giorno & Nigel Wright campaign shut Doug out of decision-making," Duffy wrote on April 10, 2011.
Giorno is a former chief of staff to Prime Minister Stephen Harper; Wright was then Harper's chief of staff and eventually left the job after it was revealed he gave Duffy more than $90,000 to repay the senator's expenses.
The Ignatieff story ran on April 20.
View an interactive by The Canadian Press comparing Duffy's diary entries and expense claims.