The puzzling case of the renowned Canadian infectious disease expert who tried to smuggle dangerous bacteria to China neared its end Wednesday as the disgraced scientist pleaded guilty to 11 charges.

Klaus Nielsen, 68, a one-time lead researcher at the Canadian Food Inspection Agency, remains free on bail until his sentencing, expected later this year.

A statement of facts, agreed to by Nielsen's lawyers and the Crown, provided fresh details of Nielsen's ill-fated attempt to take vials of Brucella bacteria to China in his luggage two years ago — a venture that resulted in him being strip-searched and hosed down with anti-contaminants in a roadside hazmat tent.

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But it still left one question largely unanswered: Why did Nielsen put his 32-year career and stellar reputation as a scientist on the line?

There is no evidence that Nielsen actually profited from starting up a company with another CFIA researcher to make and sell test kits for brucellosis, an infectious and debilitating disease caused by Brucella.

People come down with the disease when they're in contact with infected animals or animal products contaminated with the bacteria.

Animals most commonly infected include sheep, cattle, goats, pigs, and dogs. Canada eradicated brucellosis in the 1980s, though cases regularly crop up in developing nations.

Nielsen was considered an expert in the field of animal brucellosis and, indeed, had spent much of his career working to eliminate the risk of Brucella infection.

He wrote a book on the disease, and in 2010, he and his alleged partner in crime, Wei Ling Yu, published an article about new methods of brucellosis detection in the Croatian Medical Journal. Yu was hired by the CFIA in 2011.

That same year, after more than three decades as a federal government employee, Nielsen was fired from the agency following an internal investigation that "deemed that his activities had been in direct contravention of his responsibilities with the CFIA and as a public servant for the government of Canada," said the statement of facts.

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Undercover police, tipped off by the CFIA months earlier, had Nielsen under surveillance when they pulled him over on his way to the Ottawa airport for a trip to China.

With his wife in the passenger seat, they discovered in his suitcase 17 vials of live Brucella — contained in a block of ice and swathed in bubble wrap in a children's lunch bag — and a substantial quantity of goat's blood.

RCMP and Ottawa Fire Services set up a controlled zone and Nielsen was soon taken to a hazmat tent, strip-searched and sprayed with a decontamination solution.

On Wednesday, Nielsen entered a guilty plea in Ontario Superior Court to a charge of breach of trust for trying to commercialize CFIA property, and to charges of unsafe transportation of a human pathogen.

In an elaborate scheme that was first conceived in 2005, according to the statement of facts, Nielsen and Yu were angling to use Brucella "for the commercial manufacture of brucellosis test kits by his and Yu's company," the Peace River Biotechnology Company.

"He concealed the pathogen in his luggage in a manner that would not have caused an innocent third party to exercise caution with its contents, and in doing so showed a wanton and reckless disregard for public safety," says the statement.

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The statement also provided details of email records that showed Nielsen used CFIA's intellectual property to build the brucellosis kits, and evaded taxes by making it appear as though his company was headquartered in China.

It also alleges that Yu used an alias, Lucy Zhang, to attempt to bribe a public official working as a research scientist at a branch of the Kazakhstan health ministry.

Yu, posing as Zhang, offered the official a cash "performance bonus" if her institution sent money to finalize a deal with the Peace River Biotechnology Company, the statement says.

Neither Yu nor Nielsen had previous criminal records. Yu is believed to be at large in China, while Nielsen could face 10 years in prison.