David Radler, the one-time top Conrad Black lieutenant who testified against his longtime business partner, began serving his 29-month sentence Monday at a Pennsylvania jail.

But Radler's jail time could be drastically cut if he's transferred to a Canadian facility.

His sentence was part of a plea bargain made with U.S. prosecutors to testify against Black and other former company executives about how shareholders were swindled through non-compete payments. In July, Black was convicted by a jury of fraud and obstruction of justice and sentenced to 6½ years in federal prison.

As part of Radler's deal, the former president at Hollinger International pleaded guilty to one count of fraud. Prosecutors agreed to recommend that Radler be sentenced to 29 months.

But most importantly, prosecutors said they would not oppose Radler's request to be transferred to a Canadian jail. Under more lenient Canadian parole rules, Radler could serve as little as six months if he serves his time in Canada. Under federal U.S. parole rules, he would have to serve at least 85 per cent of his sentence.

Radler had to enter the U.S. system before he could request a transfer to Canada. He entered the Moshannon Valley prison in Pennsylvania on Monday.

Felicia Ponce, a spokeswoman with the U.S. Bureau of Prisons, told the Canadian Press that Radler will be fingerprinted, given a medical and mental evaluation and undergo a search as soon as he's admitted to prison.

Inmates able to work are assigned a job such as groundskeeper, food service worker or inmate orderly. They earn anywhere from 12 to 40 cents an hour.

Observers of the Black trial said it was Radler's testimony — although considered problematic at times — that secured the convictions against Black.

On Friday, a U.S. federal Appeal Court denied Black's emergency request to remain free on bond while appealing his sentence.

With files from the Canadian Press and the Associated Press