Former LA general manager Doug Dowie pleaded not guilty to charges that he directed a conspiracy to defraud public and private clients by padding bills.
The US District Attorney's Office (USDAO) has charged Sugerman, who left F-H to start his own firm in 2002, with three counts of wire fraud, and has entered a plea agreement.
Sugerman could face 15 years in prison. However, USDAO public affairs officer Thom Mrozek said the accused was aiding investigators and a sentencing recommendation would reflect his degree of co-operation.
Sugerman will appear in court on 5 July for sentencing. He has admitted to helping F-H fraudulently overcharge the LA Department of Water and Power (DWP) by $120,000, while working 'at Dowie's direction', according to the USDAO.
Dowie's trial date has been set for 2 August. He is free on a $75,000 bail after surrendering his passport.
The charges against Dowie are part of an amended complaint issued earlier this year against former F-H employee John Stodder Jr, who took over the agency's LA public affairs practice after Sugerman left. Dowie was indicted on one count of felony conspiracy and 15 counts of felony wire fraud last week. The conspiracy charge carries a maximum penalty of five years' jail.
In February, Stodder was indicted on 11 counts of wire fraud, pleading not guilty. Stodder and Dowie are expected to face trial together.
They are accused of adding $300,000 to DWP's bills between 2000 and 2004.