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 already were 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 Senator Robert Menendez of New Jersey 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 on Tuesday showed, he was photographing the people behind her, seated at the senator’s table. The couple were members of an F.B.I. surveillance team, and they had deliberately sat near Mr. Menendez and his group, which also included an Egyptian government official.
The undercover F.B.I. 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 Ms. Menendez, referring to the senator, ask the group, “What else can the love of my life do for you?”
The extraordinary scene of a U.S. senator under F.B.I. surveillance in an upscale restaurant, Morton’s The Steakhouse, not far from the Capitol was detailed by Ms. Williams-Thompson in testimony at Mr. Menendez’s federal corruption trial in Manhattan.
Ms. Williams-Thompson said she and a partner conducted surveillance for roughly two hours at the restaurant. The overheard comment by Ms. Menendez has featured prominently in the prosecution’s case.
The Menendezes and two New Jersey businessmen — 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 Ms. Menendez arranged for her husband and Egyptian officials.
The trial of Mr. Menendez, Mr. Hana and Mr. Daibes in its fourth week; Ms. 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.
Mr. Menendez, who filed on Monday to run for re-election 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 F.B.I. special agent who had executed a court-authorized search of a safe deposit box belonging to Ms. 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 Agent Frenzilli, one of Mr. 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 Mr. Menendez’s defense strategy. During the trial, his lawyers have cast Ms. Menendez as short on cash and eager to collect luxury items, like the Mercedes, and have said that Mr. Menendez knew nothing of her financial troubles and requests to friends for money.
Mr. Weitzman noted that the bank’s log book showed that only Ms. Menendez had ever opened the box. He asked Agent Frenzilli if she had ever seen the senator’s name on any of the envelopes or found any passports belonging to Mr. Menendez in the box.
No, the agent replied.
One of those envelopes, on which someone had scrawled “$10,000,” contained DNA that matched a sample taken from Mr. Daibes, one of the senator’s co-defendants, according to testimony Tuesday from Charity Davis, a forensic DNA examiner at the F.B.I. Mr. 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 F.B.I. surveillance of Mr. Menendez and others at his restaurant table that appeared to most rivet members of the six-man, six-woman jury.
During cross-examination, Ms. Williams-Thompson, in response to questions from another of the senator’s lawyers, Adam Fee, said she had not seen anything to suggest Mr. Menendez and his fellow diners were aware of the F.B.I. surveillance or were trying to avoid being watched.
Ms. 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 — to “dress the part,” she said. If she was following someone on a college campus, she would dress like a student: “jeans, backpack, the whole nine yards,” she said.
She also studied the life patterns of individuals she was assigned to follow: what time they left their homes or offices, how fast or slow they drove, little everyday things about their behavior, she said.
She said 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 then. It was unclear in court whom she was referring to, except that it was not the senator.
She suggested that the F.B.I. had more than one team of investigators inside and outside Morton’s participating in the surveillance. (Her team was over half a dozen people, she said.)
She and Mr. 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.
Ms. Williams-Thompson told the jury that she and Mr. 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 F.B.I. is there because then it won’t be committed.”
They acted like ordinary customers to maintain their cover with the Morton’s staff as well as with the people at the next table. “We dined just like them,” Ms. Williams-Thompson said.
When a prosecutor, Lara Pomerantz, asked whether they had eaten, Ms. 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.”
Judge Stein interjected: “I hope the F.B.I. paid for your meal.”
“Oh yes, sir, they did.”