Correction: An earlier version of this article said former Prince George’s County official Karl Granzow offered bribes to public officials between 1997 and 2008. The statement of facts filed in U.S. District Court in Greenbelt said that Granzow was part of a conspiracy that offered the bribes; it did not specify which member of the conspiracy offered the bribes. This version has been corrected.

A former Prince George’s County official with ties to the development community has pleaded guilty to extortion as part of a scheme that involved bribing public officials and making illegal campaign contributions to former U.S. Senate candidate Michael S. Steele, former congressman Albert R. Wynn and several others.

Karl Granzow, 46, who started as a volunteer firefighter and rose through the ranks to become deputy chief, pleaded guilty to extortion and tax evasion in federal court in Greenbelt on March 30, according to officials. The plea was unsealed Monday.

Granzow is among more than a dozen people — including former county executive Jack B. Johnson; his wife, County Council member Leslie Johnson (D-Mitchellville); former housing director James Johnson; and three prominent developers — who have pleaded guilty in a sweeping corruption scandal in Prince George’s.

The plea deal does not imply any wrongdoing by Steele, Wynn or any other candidate.

Wynn (D) said he was unaware of the illegal contributions and was uncertain whether he knew Granzow.

“I have thousands of donors,” he said. “There are people that I don’t know and people that I don’t recall. What I know is available in the public record.”

According to his guilty plea, Granzow concealed campaign contributions to state and local officials to bypass legal donation limits. Granzow, Patrick Q. Ricker and Daniel I. Colton, who are listed as co-conspirators, also recruited “straw donors,” family members and employees, to make state and federal campaign contributions for them.

Ricker pleaded guilty Dec. 30, 2009, to conspiring to commit honest services fraud, making false statements to the Federal Election Commission and tax evasion. Colton pleaded guilty to conspiracy to commit extortion and lying to the FEC. His plea was unsealed last month.

According to the court documents, Wynn received $34,000 from Granzow, Ricker, Colton and the straw donors between 2005 and 2007.

Steele, a former lieutenant governor and former chairman of the Republican National Committee, could not be reached for comment. The court documents say the Senate candidate’s campaign unwittingly filed a false quarterly report in 2006 that showed that straw donors contributed $2,000 each to his campaign when the contributions actually were made by Granzow, Ricker, Colton and another unnamed co-conspirator.

Timothy Maloney, Granzow’s attorney, would not comment.

Federal officials say Granzow, Ricker and Colton also offered bribes to public officials, including money, trips, meals, drinks, hotel rooms, flights, rounds of golf, jobs and mortgage payments to gain favorable approvals on their Greenbelt Metropark development.

All three have a financial stake in the Greenbelt Metropark, which would have produced housing, retail and commercial space near the Greenbelt Metro station. The 240-acre project is in flux. It has been on the county planning books for more than 10 years, but now it is unclear whether it will be built.

According to the plea deal, Granzow was part of a conspiracy that offered the bribes from 1997 through Sept. 11, 2008.

“Citizens have a right to expect government officials to make decisions based on the public good rather than their personal interests,” U.S. Attorney Rod J. Rosenstein said Monday in a statement announcing the plea deal. “For more than a decade, these defendants conspired to influence Prince George’s County government through a variety of corrupt schemes that had one thing in common: providing undisclosed personal benefits to government officials.”

In exchange for the bribes and contributions, officials agreed to take actions favorable to the developers, according to the plea deal.

Those actions included obtaining an approval letter for the project’s site plan, providing the developers with privileged county information, and making sure that the project was approved by officials at the state and local levels, according to court papers filed with the plea deal.

In May, Jack Johnson, 62, pleaded guilty to extortion and witness- and evidence-tampering. Under the terms of his deal, Johnson admitted that he took more than $400,000 in bribes and began shaking down developers shortly after he took office in 2003.

Last month, Leslie Johnson, 59, pleaded guilty to witness-tampering and destruction of evidence, a felony. She tried to hide $79,600 in cash in her bra and underwear as FBI agents knocked at the door of the couple’s home in November. The Johnsons were arrested that day.

The illegal contributions were made to Vision for 2006, which included Jack Johnson, former delegate Obie Patterson (D) and former County Council member Marilynn M. Bland (D), and to the Twenty-Third Team Slate, which includes 30 candidates for state and local office.

During the scheme, Granzow provided $30,000 to $70,000 in illegal contributions and property to public officials. He also pleaded guilty to failing to report $225,974 in income on his federal returns, resulting in a tax loss of $74,191.

Granzow faces 10 years in prison for both offenses. No sentencing date has been scheduled.