A federal judge has postponed the sentencing of former Gwinnett County Commissioner Shirley Lasseter and two others amid a continuing corruption investigation.

The U.S. Attorney's Office on Friday asked U.S. District Judge Charles Pannell Jr. for a delay of at least 30 days, citing to the need to "facilitate matters related to the defendants' cooperation" in the ongoing investigation. On Monday Pannell rescheduled the sentencing from Aug. 6 to Sept. 5.

The move could signal more arrests are forthcoming, according to Paul Monnin, a criminal defense partner with DLA Piper who formerly worked in the public corruption and government fraud section of the U.S. Attorney's Office in Atlanta.

In a recent interview, Monnin said if someone like Lasseter is out on bond and prosecutors seek a delayed sentencing, they likely want that person sentenced at the same time that other defendants under investigation are charged.

"I would attribute that to the government and defendant jointly being of the view that it makes sense to push the sentencing hearing back so the defendant can be accorded more cooperation credit without the government having to prematurely disclose the details of its investigation," Monnin said.

He added that usually means "another arrest would be forthcoming."

On May 31 Lasseter resigned her office and pleaded guilty to a federal bribery charge. She admitted she accepted $36,500 in cash from an undercover FBI agent posing as a businessman in exchange for her vote for a proposed real estate development on Boggs Road.

Her son, John Fanning, and Hall County businessman Carl "Skip" Cain also pleaded guilty to bribery and drug charges. In addition to their involvement in the bribery scheme, court records indicate they possessed and intended to distribute four kilograms of purported cocaine.

All three have been cooperating with investigators and could get reduced sentences as a result. U.S. Attorney Sally Yates has called the investigation "an ongoing effort to root out public corruption in Gwinnett County."

The prospect of more damning revelations has rattled a county that has seen two other county commissioners resign in recent years.

In 2010, a grand jury investigating dubious land deals indicted then-Commissioner Kevin Kenerly on a bribery charge. Jurors claimed Kenerly accepted or agreed to accept $1 million to arrange for Gwinnett to buy land from developer David Jenkins.

Kenerly resigned his commission seat but maintained his innocence. The bribery charge is still pending.

Charles Bannister, then chairman of the County Commission, also resigned in 2010 to avoid a perjury charge stemming from the same grand jury investigation.