The trial of two former top Ogilvy & Mather executives heard testimony from a former senior colleague who has already admitted defrauding the US government.

Robert Zach, erstwhile O&M strategic planning director on the Office of National Drug Control Policy account, told the Manhattan court that the over-billing of time spent on the $700 million (€540m, £372m) business was done to make up revenue shortfall.

Zach claims Shona Siefert and Thomas Early, both former senior partners at the New York-based agency, were so desperate to close the estimated $3m gap that they suggested the media department fast-track its new employees and bill their time entirely to the ONDCP, regardless of what accounts they in fact worked on.

Zach, who is testifying for the prosecution in the hope of a reduction in his sentence, alleges Siefert and Early were part of a large scale effort in 1999 to revise already submitted time-sheets and lie about future ones. He says they asked for the documents to be "reevaluated".

Siefert and Early have pleaded not guilty to the charges. If convicted they face up to five years in jail.

Cross-examining Zach, the pair's defence lawyers hammered away at his credibility, grilling him about lies he told to federal investigators probing the ONDCP case, and also quizzed him on his own role in revising the timesheets.

They implied that Zach's part in the conspiracy was motivated by fear of not getting a bonus.

But Zach insists the anger of Early and O&M co-president Bill Gray over the revenue shortfall sparked the alleged timesheet deception.

Data sourced from AdWeek (USA) and; additional content by WARC staff