A co-owner of a Langley Park liquor store admitted Thursday in federal court that he gave money and other things of value to former Prince George’s county executive Jack B. Johnson in exchange for official favors.

Amrik S. Melhi, 51, who pleaded guilty to a felony conspiracy charge in U.S. District Court in Greenbelt, also admitted that he participated in a scheme to distribute black-market alcohol.

The guilty plea stems from a sweeping federal corruption probe in Prince George’s County targeting the activities of current and former county officials, police officers, developers and business people.

The investigation became public in November when federal agents arrested Johnson and his wife, Leslie, a member of the County Council. Authorities said the couple conspired to flush a $100,000 check from a developer down the toilet as FBI agents knocked on the door of their home in Mitchellville.

Johnson, a Democrat who served two terms as county executive, pleaded guilty in May to extortion and witness tampering, admitting that he took more than $400,000 in bribes from a developer. He is scheduled to be sentenced in September.

Leslie Johnson, 59, is charged with conspiracy to commit witness and evidence tampering. She remains on the council while the case against her is pending.

Melhi and his wife, Ravinder K. Melhi, 49, own Tick-Tock Liquors and Restaurant in Langley Park, Langways Liquors in Lanham and Decker’s Liquors in Bel Air, federal prosecutors said.

According to a plea agreement, Amrik Melhi gave Johnson money, campaign donations and other things of value. In return, Johnson used his power to help Melhi pass permit inspections and obtain licenses and influenced legislation beneficial to Melhi’s businesses.

In a court hearing in November, a federal prosecutor said authorities were investigating the alcohol scheme, using wiretaps, when they learned Melhi may have bribed county officials. They did not elaborate at the time.

According to the plea agreement, Amrik Melhi also purchased contraband alcohol for his stores, allowing him to avoid paying Maryland taxes. He paid co-conspirators, including a former Prince George’s County police sergeant who was part of the scam.

As part of the agreement, Melhi will forfeit more than $975,000 in cash found in his home and in various bank accounts, and the government will not seize the couple’s property and businesses, Assistant U.S. Attorney David Copperthite said.

Ravinder Melhi also pleaded guilty to a felony charge Thursday, admitting that she asked a police officer involved in the scheme to use the Maryland Motor Vehicle Administration database to find a customer whose check bounced.

Amrik Melhi will be held at a correctional treatment facility until his Sept. 12 sentencing, said his attorney, Edward J. Leyden. He faces up to 20 years in prison.

Ravinder Melhi will return home, where she will be removed from house arrest in the coming days, according to her attorney, Larry A. Nathans. She faces up to five years in prison and is scheduled to be sentenced Oct. 11.

The couple have three children, one of whom is a minor.

About two dozen family members and friends attended the hearing. As the prosecutor read the statement of facts, several held back sobs.