Prince George’s County Council Member Leslie Johnson (D-Mitchellville) on Thursday admitted destroying evidence in a far reaching federal corruption probe.

Prince Georges County Council member Leslie Johnson (center) held the hand of her lawyer Shawn M. Wright (left) as they walked to the entrance of the U.S. District Court on June 30 in Greenbelt, Md. Johnson pleaded guilty to the charge of conspiracy to commit witness and evidence tampering in order to obstruct a federal corruption investigation. (Mark Gail/THE WASHINGTON POST)

She admitted that she flushed a $100,000 check from a developer down the toilet and stuffed $79,600 in her underwear to hide it from federal agents who were knocking at the door. It happened Nov. 12, the day she and her husband, former county Jack B. Johnson (D), 62, were arrested as part of an investigation into whether county officials accepted and solicited bribes.

“There is nothing I can do or say that would make this day any less difficult,” Johnson said Thursday outside the courthouse. She asked that she be defined not by “this mistake” but by the “countless days, months and years” spent helping people of the county.

“I look forward to continuing to serve and help the lives of those in need,” Johnson said.

Johnson’s lawyer, Shawn M. Wright, said Johnson intends to remain in office until she is sentenced Oct. 13. Under Maryland state law, elected officials convicted of felonies must step down from office but the conviction is not final until sentencing. Several candidates already have said they would run if a special election is held to fill Johnson’s seat.

Johnson, a former administrative law judge in the District, became the 12th person convicted in public court in the sweeping corruption case.

Last month, Jack Johnson, who ended his second term in December, admitted he accepted more than $400,000 in bribes while in office. Three developers, two Prince George’s police officers, the county’s former housing director and four others also have pleaded guilty in connection with the probe, which also revealed a ring trafficking contraband alcohol and cigarettes.

United States Attorney for the District of Maryland Rod J. Rosenstein (left) talked with reporters after the guilty plea of Prince Georges County Councilwoman Leslie Johnson on June 30, 2011 in Greenbelt, Md. (Mark Gail/THE WASHINGTON POST)

Jack and Leslie Johnson were well known in the Prince George’s community and beyond. In June 1992, the Johnsons appeared on the cover of the New York Times magazine in an article touting Prince George’s County as a mecca for educated, black professionals. Jack Johnson served two terms as state’s attorney and two more as county executive, and never lost an election. Before the arrests last fall, he ordered the publication of thousands of copies of a soft-cover book, at a cost of $250,000 to taxpayers, touting the successes of his administration.

Leslie Johnson, her husband’s longtime political confidante, seemed poised for a promising political career after she defeated a handful of opponents in the September Democratic primary with more than 40 percent of the vote. She was unopposed in the general election last November. Just ten days after her election, both Johnsons were arrested by FBI agents at their Mitchellville home.

Always well-coiffed and elegantly dressed, Johnson remained on the County Council after her arrest, and her colleagues have privately marveled about her ability to show no public anxiety about her court case. Even though her colleagues had barred her from serving on committees and handling development issues in her district, she has asked probing questions of council witnesses discussing everything from health care to stormwater management, and has generally inserted herself in council proceedings and deliberations.

As recently as Wednesday night, her council office sent out an invitation to a July 23 “business card exchange” for residents to meet with county officials who handle small-business issues, and minority contracting.

Johnson had been scheduled to attend a court hearing early last month, where she was expected to plead guilty. That hearing was suddenly canceled two days before it was to take place.

On Thursday, Johnson appeared stoic and said little during the hearing before U.S. District Judge Peter J. Messitte.

“Are you pleading guilty became you are guilty and no other reason,?” Messitte asked.

“Yes sir,” Johnson replied.

Johnson is scheduled to be sentenced Oct. 13. Messitte said in court that guidelines call for a sentence of 12 to 18 months.

This post has been updated.