Federal agents were at the offices of the Prince George’s County liquor board Thursday. (Bonnie Jo Mount/TWP)

Two liquor store owners looking for an advantage with Sunday sales bribed public officials in a scheme that involved money drops in the men’s restroom of a restaurant and bank deposits by an elected official who pulled stacks of cash from his pockets, federal prosecutors said Thursday.

Four people were charged in federal court in connection with what prosecutors said was a long-running conspiracy that paid off a Maryland state lawmaker and officials with the Prince George’s County liquor board.

Two people with the liquor board and two business owners in the county are accused of conspiring to influence public officials, and the investigation included undercover FBI agents, wiretaps and an envelope of cash stashed in a car’s glove compartment.

Among those charged were David Dae Sok Son, 40, the liquor agency’s administrator, and board commissioner Anuj Sud, 39, a College Park lawyer.

“The defendants allegedly paid cash bribes to state and local officials in Prince George’s County in return for favorable action concerning liquor licenses,” Maryland U.S. Attorney Rod J. Rosenstein said in a statement. “Our government is not supposed to work that way.”

[Read the charging document for liquor board director David Dae Sok Son ]

Prosecutors assert that the conspiracy dates from at least 2012 and extended through 2015, and includes a series of bribes, ranging from $1,000 to $5,000. Rosenstein said Thursday that the investigation is ongoing. At least two more government officials are expected to be charged, according to court papers filed in U.S. District Court in Greenbelt.

The affidavit does not name the officials but describes them as a former elected official and a state delegate, who is a member of the House Economic Matters Committee who voted to extend Sunday alcohol sales in 2015.

[Read the charging document for liquor board commissioner Anuj Sud]

The arrests of the Prince George’s businessmen and public officials extend the county’s troubled history of pay-to-play politics, a history that second-term County Executive Rushern L. Baker III (D) has fought to leave behind since succeeding disgraced former county executive Jack B. Johnson (D).

Baker vowed to “root out any and all county employees or appointees that are involved in any nefarious activity.” He said he is concerned that “the perception of corruption will be directed at the county government, setting us back in our war against unethical and illegal behavior.”

Johnson, Baker’s predecessor, was county executive from 2002 to 2010 and pleaded guilty to extortion and witness and evidence tampering after masterminding a corruption conspiracy in which prosecutors said he received more than $1.6 million in bribes. His wife, Leslie Johnson, made headlines when she flushed a $100,000 check down the toilet and hid $79,600 in cash in her underwear as federal agents pounded on the couple’s front door.

[Former Pr. George’s executive asks for corruption conviction to be set aside]

At the heart of the conspiracy outlined in court papers Thursday is the Board of License Commissioners, a state entity that regulates the sale of alcohol in the county at more than 600 liquor stores, restaurants and other businesses. The board’s five commissioners are appointed by the governor to three-year terms.

Gov. Larry Hogan (R), who appointed Sud in 2015, called the situation “a mess” and said that Sud should resign immediately in light of the allegations.

“It probably wouldn’t be a bad idea if we had the entire liquor board in Prince George’s County resign over these disgraceful things,” Hogan said.

Son, the current director of the board, was a commissioner from 2005 through 2014 and is accused of soliciting and arranging bribes from lobbyists and business owners, including being a middleman in arranging a $4,000 payment from a businessman to an elected official in the men’s bathroom of a restaurant.

An affidavit filed by a federal agent describes a series of bribes paid in return for government grants and to push through legislation to expand liquor sales in the county.

During the 2015 Maryland legislative session, Son served as a liaison for the county’s Senate delegation, the charging documents state. Son specifically worked with lobbyists and business owners who were interested in the passage of a bill to allow up to 100 permits to sell alcohol on Sundays in Prince George’s County.

Son allegedly asked an unnamed elected official to help get the bill passed by pressuring one of his colleagues. Both officials subsequently voted in favor of the bill, according to prosecutors.

Two business owners also were charged Thursday: Young Jung Paig, 62, the owner of Central Avenue Restaurant & Liquor Store and Shin Ja Lee, 55, owner of Palmer Liquor Store.

After Hogan signed a Sunday sales bill into law in April 2015, prosecutors said Son arranged a lunch with Paig, Lee and the elected official whose help he had sought. During the lunch, prosecutors said Son told the elected official to meet Paig in a men’s bathroom, saying, “He’s going to hook you up, alright?”

In the bathroom, Paig allegedly handed the elected official a white envelope with $3,000 in cash and another envelope with $1,000. The official was working as an informant for law enforcement at the time, but stopped cooperating in July 2015, according to the affidavit. The official has agreed to plead guilty to bribery charges, according to the filing.

Prosecutors said Son later received a $4,000 payment from a lobbyist for his help in getting a client a Sunday license.

In November 2015, a second elected official who helped push the Sunday sales bill went with Son to a Panera Bread restaurant in Bowie with the two liquor store owners, according to the affidavit. When the four left the restaurant, the state delegate got in the car with Paig.

FBI agents watched as the delegate immediately drove to the Capital One Bank in the same shopping complex. He pulled up and deposited $2,000 in the drive-through ATM and went inside to deposit another $2,000 with the teller, according to surveillance footage and bank records.

Son did not enter a plea during his brief appearance in court Thursday. Prosecutors said he had agreed to work for law enforcement as an informant, but then allegedly began tipping off other targets. Son was the only one of the four arrested ordered to remain in federal custody due to fears from prosecutors that he would further obstruct the case. Son’s attorney Christopher Nieto disputed the prosecutors’ characterization.

Sud, who is accused of taking cash bribes in exchange for votes on liquor board matters, also made a brief court appearance Thursday and was released until his next hearing.

In his legal practice, Sud has represented a company that federal and state agencies have said violated the law when it targeted victims of lead-paint poisoning in scores of financial deals that made the company millions of dollars.

[Authorities: Company that reaped millions from lead-poisoning victims violated law]

The business owners, Lee and Paig, were also released under pretrial supervision after appearing in court Thursday.

Before the charges were filed, federal agents on Thursday morning searched the Largo offices of the liquor board, interviewing workers and gathering documents in the offices of the agency’s fourth-floor suite on Basil Court, in a Largo office park.

Last month, the board’s chairman, Charles W. Caldwell III, resigned after being arrested on drunken-driving charges outside the MGM National Harbor on the casino’s opening night.

Caldwell took the helm of the agency in March 2015 after a standoff with his predecessor, Franklin D. Jackson, who said he was never properly notified that he was being replaced.

Fenit Nirappil, Ovetta Wiggins, Josh Hicks, T. Rees Shapiro, Jennifer Jenkins, Cheryl W. Thompson and Hamil R. Harris contributed to this report.