A private investigator accused of bribing 15th Judicial District Attorney’s Office employees with cash and gifts to secure special treatment for DWI offenders pleaded guilty Monday as a jury was being selected for his federal trial.

Robert Williamson, who marketed his investigation business as Secret Cajun Man Limited, pleaded guilty to charges of conspiracy, bribery and Social Security fraud in an investigation that had already netted guilty pleas from five others, including three former employees of the District Attorney’s Office.

Williamson admitted to receiving at least $443,000 from 2008 to 2012 to set up the special plea deals, though some of that money was used to pay fines and other expenses for his clients, according to court documents filed after his guilty plea.

“This is a win for the people of our community who no longer have to be concerned about drunk drivers subverting the criminal justice system,” U.S. Attorney Stephanie Finley said in a written statement.

Williamson, 64, faces up to 10 years in prison on the bribery charge and up to five years each on the charges of conspiracy and Social Security fraud.

The latter charge was for not reporting the fees he received for arranging the special plea deals, income he was required to disclose to the government because he was receiving Social Security disability benefits.

The plea came Monday afternoon as 60 potential jurors awaited the start of jury selection.

Williamson, who has health problems and now walks with a cane, left the courtroom without comment.

“My client has decided to accept responsibility and plead to get this over for himself and his family,” said his attorney, Thomas Damico.

Williamson was accused of charging cash fees to his clients and using some of that money to pay off employees of the District Attorney’s Office to secure plea deals allowing for a speedy disposition and for the charges to be wiped from the public record.

Most of the special plea deals were for DWI defendants.

Fifteenth Judicial District Attorney Keith Stutes made the scandal a central issue in an election campaign that ended last year with the defeat of former District Attorney Mike Harson, who had held the seat for two decades.

Harson was not identified as a target of the investigation, but federal prosecutors wrote in court filings that the scheme was carried out without the DA’s knowledge because of a “lack of oversight and safeguards.”

His longtime secretary, Barna D. Haynes, pleaded guilty to a federal conspiracy charge in 2013 for working with Williamson to set up the plea deals.

In court filings Monday, Williamson admitted paying her at least $55,000, at $500 per case.

Former Assistant District Attorney Greg Williams and his secretary, Denease Curry, also have pleaded guilty.

Williams admitted accepting $500 and a series of gifts, including an autographed New Orleans Saints hat, bicycles for himself and his family members, and clothing. Curry admitted accepting about $1,600 for working with Haynes to coordinate plea deals for Williamson.

The investigation also brought guilty pleas from two former employees of the Acadiana Outreach Center, Sandra Degeyter and Elaine Crump.

Degeyter admitted falsifying certifications showing criminal defendants had completed court-mandated community service at the nonprofit agency, which at the time provided assistance for the homeless and recovering addicts.

Crump pleaded guilty to misprision of a felony for not reporting the scheme when she became aware of it.

All five of those defendants agreed to cooperate with federal prosecutors, and some were expected to testify had Williamson gone to trial.

Williamson is set for sentencing on Sept. 25.

Finley said Williamson’s guilty plea concludes the federal corruption investigation, but a separate state investigation related to the scandal is pending.

The Louisiana Attorney General’s Office has offered no details on who or what state authorities are scrutinizing.

Assistant Attorney General David Caldwell, who leads the agency’s public corruption division, said last week that the case remains active and he expected “some movement in the near future.”

The federal investigation became public in February 2012, when the FBI searched the District Attorney’s Office in Lafayette.

According to court filings, the FBI was already months into the investigation at the time and had been monitoring Williamson’s phone calls since September 2011.