(Bloomberg) -- A federal judge began a hearing on whether Paul Manafort, President Donald Trump’s former campaign chairman, lied to investigators after he pledged to cooperate with Special Counsel Robert Mueller.

Manafort, who has been in jail since June, appeared Friday at the hearing in federal court in Washington, where prosecutors say he lied during a dozen debriefings after pleading guilty on Sept. 14. One of the areas that prosecutors say he lied about was his contacts with a former business associate whom Mueller says has ties to Russian intelligence.

U.S. District Judge Amy Berman Jackson convened the hearing to determine whether Manafort, 69, breached a plea deal he struck with prosecutors. Berman’s decision could influence how harshly she sentences Manafort in March on two conspiracy counts, which carry a maximum of 10 years in prison.

Manafort will be sentenced separately on Feb. 8 in Alexandria, Virginia, where a federal jury convicted him in August of bank and tax fraud.

The hearing came hours after the arrest of Roger Stone, Manafort’s former partner in a political consulting business, who was charged with lying, witness tampering and obstructing Mueller’s investigation into whether Trump’s campaign coordinated with Russians who interfered in the 2016 election.

To contact the reporters on this story: David Voreacos in federal court in Newark, New Jersey, at dvoreacos@bloomberg.net;Andrew Harris in Washington at aharris16@bloomberg.net;Carlyann Edwards in Washington at cedwards136@bloomberg.net

To contact the editors responsible for this story: Jeffrey D Grocott at jgrocott2@bloomberg.net, Joe Schneider

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