Shona Seifert was "at the heart and the pinnacle of the conspiracy" to overbill the White House Office of National Drug Control Policy, according to prosecutors. And last week, Judge Richard M. Berman agreed, heaping a heftier sentence upon Seifert than on her co-defendant, Thomas Early.

Berman sentenced Seifert, 44, former executive group director at Ogilvy & Mather, to 18 months in a minimum-security prison in Danbury, Conn.—four months longer than former finance director Early —because as a hands-on manager, Seifert was responsible for a "slippage in ethics," he said.

Seifert and Early were convicted in February on 10 counts of fraud and conspiracy. During the trial, witnesses testified that Seifert asked them to doctor timesheets. "Because of their trust and respect for Ms. Seifert, they made the changes ... and put themselves in legal and ethical jeopardy," Berman said in U.S. District Court in lower Manhattan.

Seifert also was ordered to pay $126,000 in fines and fees and perform 400 hours of community service. She must also write a code of ethics for the ad industry, something Berman said was sorely missing.

As a British citizen, Seifert is eligible for deportation upon her release, former prosecutor Douglas Tween said. However, her lawyer, Greg Craig, said his office had not been contacted by the Department of Homeland Security and he knew of no such plans. An Immigration and Customs Enforcement rep said Seifert is not in its database of people in removal proceedings.