The man and the woman arrived at the Washington steakhouse one evening in May 2019 and took a table on the patio, near where five diners were already seated and seemed to be enjoying themselves. Jackets were off, laughter was heard and wine was being poured. A cigarette dangled from one man’s hand.

But there was something else that stood out: Among the five were Sen. Bob Menendez, DN.J., and his future wife, Nadine Menendez.

The couple who had arrived late appeared to be on a date. She was wearing a black dress, and during their meal he moved around their table and used a camera to, it appeared, snap her picture.

But in reality, court testimony Tuesday showed, he was photographing the people behind her, seated at the senator’s table. The couple were members of an FBI surveillance team, and they had deliberately sat near Bob Menendez and his group, which also included an Egyptian government official.

The undercover FBI investigators also used concealed cameras to photograph and video-record the people at the table. The female investigator, Terrie Williams-Thompson, testified that at one point, she overheard Nadine Menendez, referring to the senator, ask the group, “What else can the love of my life do for you?”

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The extraordinary scene of a US senator under FBI surveillance in an upscale restaurant, Morton’s The Steakhouse, not far from the Capitol, was detailed by Williams-Thompson in testimony at Bob Menendez’s federal corruption trial in Manhattan.

Williams-Thompson said she and a partner conducted surveillance for roughly two hours at the restaurant. The overheard comment by Nadine Menendez has featured prominently in the prosecution’s case.

The Menendezes and two New Jersey businesspeople — Wael Hana and Fred Daibes — have been charged in a conspiracy to give the senator and his wife gold, cash, a Mercedes-Benz and other bribes worth hundreds of thousands of dollars in exchange for the senator’s agreeing. to steer aid and weapons to Egypt and to meddle in criminal cases in New Jersey.

An indictment filed last year says the dinner at the steakhouse was one of a number of meetings Nadine Menendez arranged for her husband and Egyptian officials.

The trial of Bob Menendez, Hana and Daibes in its fourth week; Nadine Menendez’s trial was postponed by the judge, Sidney H. Stein, until July because she is being treated for breast cancer. All four defendants have pleaded not guilty.

Bob Menendez, who filed Monday to run for reelection to the Senate as an independent, told reporters in Spanish as he left the courthouse Tuesday evening: “Every day we’re showing the truth. Every day we’re showing them our innocence.”

Prosecutors also presented testimony Tuesday from Anna Frenzilli, an FBI special agent who had executed a court-authorized search of a safe-deposit box belonging to Nadine Menendez at a New Jersey bank.

Inside the box, she testified, agents found 10 envelopes — some with “Nadine” written on them — containing nearly $80,000 in cash and expired passports for her and her two children.

During a cross-examination of Frenzilli, one of Bob Menendez’s lawyers, Avi Weitzman, seized on her testimony in an apparent attempt to distance the senator from his wife’s financial dealings, a central aspect of Bob Menendez’s defense strategy. During the trial, his lawyers have cast Nadine Menendez as short on cash and eager to collect luxury items, like the Mercedes, and have said that Bob Menendez knew nothing of her financial troubles and requests to friends for money.

Weitzman noted that the bank’s logbook showed that only Nadine Menendez had ever opened the box. He asked Frenzilli if she had ever seen the senator’s name on any of the envelopes or found any passports belonging to Bob Menendez in the box.

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No, the agent replied.

One of those envelopes, on which someone had scrawled “$10,000,” contained DNA that matched a sample taken from Daibes, one of the senator’s co-defendants, according to testimony Tuesday from Charity Davis, a forensic DNA examiner at the FBI Daibes is accused. of paying the Menendezes bribes in exchange for the senator’s efforts to help him in a bank fraud case.

But it was the testimony about the FBI surveillance of Bob Menendez and others at his restaurant table that appeared to most rivet members of the six-man, six-woman jury.

During cross-examination, Williams-Thompson, in response to questions from another of the senator’s lawyers, Adam Fee, said she had not seen anything to suggest Menendez and his fellow diners were aware of the FBI surveillance or were trying to avoid being watched.

Williams-Thompson, a veteran of nearly two decades with the bureau, testified that when she conducted surveillance, her job was to blend into her surroundings. She typically wore capri pants or jeans, tennis shoes and a shirt — “We have to dress the part,” she said. If she was following someone on a college campus, she would look like a student: “T-shirt, jeans, backpack, laptop, the whole nine yards,” she said.

She also studied the life patterns of individuals she was assigned to follow: where they work; what time they leave home and return; how fast or slow they drive — “just little everyday things about that individual,” she said.

She said that on the night of May 21, 2019, she and another investigator, Damein Ragland, were assigned to surveil “a subject from New York” who had come into the Washington area, whose name she did not know. She said the subject was not the senator, but rather someone who happened to eat dinner with him at Morton’s.

She suggested that the FBI had more than one investigative team inside and outside Morton’s that night; She was on a team composed of seven to eight people, she said.

She and Ragland posed as a married couple on a dinner date, and were driven to the restaurant by her team leader, who posed as an Uber driver.

They had been given a description of the subject and they viewed a photograph as well.

Williams-Thompson told the jury that she and Ragland used code names and kept their identities secret, even from Morton’s personnel.

“We don’t want to blow our cover,” she explained. “We need to make sure that if there is going to be an act done, we do not need them to know the FBI is there because then it won’t be committed.”

They acted like ordinary customers to maintain their cover with Morton’s staff as well as with the people at the next table. “We dined just like them,” Williams-Thompson said.

When a prosecutor, Lara Pomerantz, asked whether they had eaten, Williams-Thompson replied: “I sure did. It was good, too.”

“That is part of blending in,” she added. “You eat? I’m going to eat.”

Stein interjected: “I hope the FBI paid for your meal.”

“Oh yes, sir, they did.”