A Canadian naval intelligence officer has pleaded guilty to spying for Russia, a public admission of an embarrassing espionage scandal that has damaged Canada's reputation among allies and will likely reverberate for years.

In a Halifax court Wednesday, Sub-Lieutenant Jeffrey Delisle, 41, pleaded guilty to two charges under the Security of Information Act of "communicating with a foreign entity," and a Criminal Code offence of breach of trust.

His admission lifts a publication ban placed on details of the Crown's case against SLt. Delisle. A prosecutor at bail hearings in the spring said Russia was the beneficiary of SLt. Delisle's four-and-a-half years of espionage, and cited intelligence sources who feared it could push Canada's relations with allied intelligence organizations "back to the Stone Age."

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The sailor, whose last post was the ultra-secure Trinity naval intelligence gathering centre in Halifax, had access to top military secrets – databases with protected information from Canada and the country's allies through intelligence-sharing systems such as the "Five Eyes" network linking Australia, Canada, New Zealand, Britain and the United States.

SLt. Delisle, the court was told, searched military databases for the term "Russia," smuggled the details out of his office using a USB memory stick – and handed the fruits of his labours over to agents for Moscow every 30 days.

The information was mostly military but also contained reports on organized crime, political players and senior defence officials. It included e-mails, phone numbers and a contact list for members of the intelligence community.

The naval officer has been held in custody at the Central Nova Scotia Correctional Facility in Halifax since his arrest in January and will not be sentenced until early next year.

SLt. Delisle could be looking at a long stay behind bars but not life imprisonment, his lawyer suggested.

The Crown, meanwhile, will be scouring the world for case law to convince a judge that the sailor must remain imprisoned as there are no precedents in law. This is the first time anyone in Canada will be sentenced under the Security of Information Act, which was created more than a decade ago in response to the Sept. 11 terrorist attacks.

SLt. Delisle was a rare catch for the Russian government: a spy who walked in from the cold.

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It was back in mid-2007 that the Canadian Forces member first embarked on his traitorous side career. He strode into the Russian embassy in Ottawa, volunteering to sell out his country. He would earn about $3,000 a month for this service.

"I said I wanted to talk to a security officer, which are usually GRU," SLt. Delise said of Russian military intelligence, in a statement read by a Crown prosecutor this spring. "I showed my ID card. They took me into an [office] … asked me a bunch of questions, took my name and off I go."

It would be the only time SLt. Delisle would meet personally with a Russian handler on Canadian soil.

SLt. Delisle had an escape plan in place – one he never got a chance to use, the court heard. If he needed to seek refuge or re-establish contact with the Russians, he was told he could walk into a Russian embassy – preferably not the one in Ottawa – and inform them he was "Alex Campbell."

The Russians would then ask him "Did I meet you at a junk show in Austria?" And he was supposed to reply: "No, it was in Ottawa."

The "day I flipped sides," as SLt. Delisle described it to his Canadian police interrogators, came as his marriage of nearly a decade was unravelling.

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The naval officer told authorities he didn't do it for money but rather for "ideological reasons" – and was acutely aware his life as he knew it was now over.

"That was the end of my days as Jeff Delisle," the sailor said, according to the Crown prosecutor. "It was professional suicide."

The Canadian sailor was paid by wire transfer for the first four years. At first he was paid $5,000 but this quickly dropped to about $2,800 a month and then finally $3,000 every 30 days. This continued until about five months before he was caught, when the Russians changed how they paid him.

The Russians had devised a simple method for SLt. Delisle to hand over information. He and his Russian handler shared a single e-mail account on Gawab.com, a Middle Eastern provider.

The Canadian spy would log in and compose an e-mail. He'd copy and paste the stolen information into the body of the e-mail. But instead of sending the message he would save it in the draft e-mail folder and log out.

The Russians would subsequently log in to the Gawab account, retrieve the information and then write him a draft e-mail in reply – one that was saved but never sent.

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In the months before they arrested SLt. Delisle, Canadian authorities managed to break into the Gawab account and trick the sailor into leaving purloined secrets for them.

He also felt pressured to comply with the Russians, who made not too subtle threats.

"They had photos of me. They had photos of my children. I knew exactly what it was for," the Crown said SLt. Delisle told them.

The Canadian spy's relationship with Moscow began to change in late summer of 2011. It started with a trip to Brazil to meet a Russian handler named "Victor."

The Crown's narrative has gaps in it but it appeared that either the sailor or the Russians believed his ability to gather intelligence might be curtailed.

Moscow proposed that the Canadian Forces member's role change – that he become what they called "the pigeon" – the liaison between all agents in Canada working for Russia's military intelligence unit.

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The plan was eventually for SLt. Delisle to travel to Austria for more training by Moscow. He never made the trip.

Things began to fall apart on the return trip from Brazil. He was pulled aside at the airport by Canadian border officials. They found thousand of dollars in cash on him as well as thousands of dollars more in pre-paid credit cards.

The Crown alleged that Moscow wanted the Canadian sailor to lie low for a while.

By December, 2011, however – a month before he was caught – SLt. Delisle was shipping stolen secrets again.

"The publishing house is glad to hear your creative juices are flowing again," the Crown alleged that the Russians told SLt. Delisle. "Please send us your manuscript."

- With a report from Colin Freeze in Halifax

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With a report from Colin Freeze in Halifax