The government’s closely watched foreign bribery sting case that nabbed 22 arms and military equipment industry executives and employees began Tuesday here in Washington, where a prosecutor described to jurors an allegedly corrupt deal to sell $15 million worth of supplies to the defense minister of Gabon.

The prosecutor, Assistant U.S. Attorney Jonathan Haray, said the four defendants on trial — the first group to take the allegations to a jury — participated in a scheme that involved an illegal bribe to secure the supply contract with Gabon. The defendants were indicted last year in an aggressive prosecution that marked the first large-scale use of undercover techniques in a Foreign Corrupt Practices Act case.

“This was a corrupt pay-to-play business deal, and they all jumped into it,” Haray told jurors in U.S. District Court for the District of Columbia.

The men on trial — Pankesh Patel, John Wier III, Andrew Bigelow and Lee Tolleson — created two invoices to hide the illegal payment to the Gabonese defense minister, Haray said. The prosecutor described several meetings between undercover FBI agents and the defendants, including one held at a restaurant in Washington’s Chinatown neighborhood. The deal was a ruse, and Gabon did not actually participate in the investigation.

Haray told jurors they’d get to see and hear secretly recorded video and audio in which the participants in the deal agreed to an unlawful commission. An undercover agent, Haray said, posed as a middleman between the defendants and the defense minister. The recordings, he said, are the government’s best evidence.

“This was a corrupt deal, plain and simple, and they all knew it,” Haray said. At one point, Haray said the deal was “obviously” illegal.

At least one co-defendant charged in the scheme, Jonathan Spiller, who pleaded guilty in March, is expected to testify for the government.

Spiller’s attorneys include Kenneth Wainstein, an O’Melveny & Myers partner in Washington.

Kobre & Kim partner Eric Bruce, who represents Patel, a London resident who sells military uniforms around the world, told jurors the defense will center on alleged FBI misconduct during the investigation.

Bruce’s opening statement focused on the government’s alleged misuse of an informant named Richard Bistrong, who is charged separately in Washington federal district court with foreign bribery violations. Bruce attacked Bistrong’s credibility, saying he ended up controlling the FBI investigation and infecting the entirety of it.

Bruce said the FBI was so focused on making arrests that the agency ignored its own rules for fair investigations. The defense lawyer said the government deleted text messages between Bistrong and the defendants. The FBI, Bruce said, also did not record all of its meetings with Bistrong.

Bruce called Bistrong a “scoundrel” and said the government wants no part of him at trial.

FBI agents and Bistrong, Bruce said, concealed the alleged illegality of the deal with Gabon, placing talk of a commission in between innocuous statements. In court Tuesday, Bruce called the government’s tactic the “commission sandwich.”

With some 80 court observers in Judge Richard Leon’s courtroom, seating was tight Tuesday.

Several criminal defense lawyers who are handling other defendants — including attorneys David Schertler, Michael Madigan and David Krakoff — attended opening statements. The chief of DOJ’s fraud section, Denis McInerney, was also spotted in the crowd.