OTTAWA -- "What the heck is this?" was Mike Duffy's surprised reaction when he learned he'd been signed up to receive polling research reports about Atlantic Canada.

Court is hearing how the suspended senator was also on the hook for part of the cost -- and how he paid the bill is linked to the 31 charges of fraud, breach of trust and bribery Duffy currently faces.

In 2012, New Brunswick Sen. Percy Mockler signed up Duffy and three others to the Atlantic Matters reports so they could split the $5,000 cost -- too steep for any single senator's budget to cover.

Elizabeth Brouse, a former vice-president of MQO Research, which produced the reports, says Duffy didn't even know he was signed up until a welcome letter prompted his surprised query.

They told Duffy not to worry about the bill, since he'd never read the research, but he paid it anyway -- with a cheque for $1,054.66 issued by a company run by Gerald Donohue, a friend of Duffy's who allegedly ran two companies that helped Duffy get around Senate rules.

The cheques issued from Donohue's companies are the basis for several of the fraud and breach of trust charges.

Duffy's defence lawyer is arguing that the cheques covered services that were in keeping with his work as a senator.

Later today, the trial is expected to hear from two journalists who did work for Duffy and were paid by the Donohue companies.