The New Jersey attorney general’s office seized records on Thursday from Bergen County law enforcement agencies to review whether the investigation of a fatal 2018 car crash involving the soon-to-be wife of Senator Robert Menendez was handled properly, two officials said.

Nadine Menendez, who was dating Mr. Menendez at the time of the crash, was released by the police without a summons or a sobriety test after she struck and killed Richard Koop, 49, while driving at night along a wide, two-lane boulevard in Bogota, N.J., police records show.

After a brief investigation, the police determined that Ms. Menendez, 56, was “not at fault” and that Mr. Koop, who had marijuana and alcohol in his system, had been jaywalking as he walked across the street toward his apartment. Ms. Menendez told officers that Mr. Koop “jumped on my windshield”; no charges were filed.

The attorney general’s office began its inquiry a day after details of the collision were reported publicly for the first time by The New York Times and The Record of New Jersey, nearly five years after it happened. A review by The Times of police reports, dashcam footage, 911 call recordings and a video of the collision raises new questions about the rigor of an investigation that Mr. Koop’s relatives have long believed was inadequate.

The renewed scrutiny could create fresh legal and political peril for Mr. Menendez, a Democrat, and his wife, who were indicted last month alongside three New Jersey businessmen in a brazen bribery scheme. They have each pleaded not guilty, including to an allegation that the couple received as a bribe a new Mercedes-Benz convertible to replace Ms. Menendez’s car, which was damaged in the crash.

The attorney general’s public integrity unit will review all records generated by the Bogota Police Department and the Bergen County Prosecutor’s office to determine if the investigation into the fatal crash was handled appropriately, according to the two officials, who did not want to be identified because of the sensitive nature of the investigation, first reported by NBC News. New Jersey’s attorney general, Matthew J. Platkin, has authority over all police agencies and county prosecutors’ offices in the state.

Leaders of the Bogota Police Department have not returned phone calls or responded to in-person queries about the incident for days. On Thursday, an officer, Kevin Geraghty, referred a reporter to the borough attorney, William Betesh, who said he had “no comment in this matter.”

Christopher M. Kelemen, the borough’s Republican mayor, and every member of Bogota’s elected council declined to comment, citing a directive from Mr. Betesh. Several members of the council said they had been unaware of the crash or the high-profile driver involved until this week — even though state records show it was the small borough’s only traffic fatality in at least a five-year period.

Elizabeth Rebein, a spokeswoman for the Bergen County Prosecutor’s office, said she had no information to provide about the seizure of records or the attorney general’s review.

The issue briefly burst into the open at a town meeting in Bogota Thursday night when Jorge Nunez, a former council member, spoke up to say he wanted to know more about the police response. “I’m not the only one to not feel good about my community, our community,” he said.

Mary Ellen Murphy, a Democratic council member currently running for mayor, responded that it would be “irresponsible” for the borough’s leaders to comment before they knew more.

“By the advice of our attorney, we must heed the advice of the attorney,” she said.

Neither Mr. Menendez nor his wife had ever reached out to the Koop family to express condolences. Ms. Menendez’s lawyer, David Schertler, said Mr. Koop’s death was a “tragic accident” unrelated to the federal bribery charges.

“I have to believe that the police did an investigation and exonerated her and found that she wasn’t at fault,” he said earlier this week.

All of it comes just weeks after federal prosecutors in Manhattan charged the senator and his wife in a wide-ranging 39-page indictment. Prosecutors said the couple accepted bribes including bars of gold bullion and mortgage payments in exchange for Mr. Menendez’s using his political clout to stifle criminal investigations and to steer aid and weapons to Egypt.

Though they did not share details of the fatal December 2018 collision, prosecutors said in the indictment that Ms. Menendez had been in an “accident” that month that left her without a car. They said that the senator then agreed to try to halt a state criminal investigation tied to an associate in exchange for a $60,000 Mercedes-Benz C-300 convertible.

Mr. Platkin’s office had previously announced it would investigate the senator’s alleged effort to interfere with the state investigation. That review will be expanded to include a review of the fatal crash that preceded it.

A spokeswoman for Mr. Platkin had no comment about the inquiry.

Ms. Menendez’s car struck Mr. Koop as he was walking toward his home after being dropped off on the opposite side of the street, according to his relatives and police records. His body was thrown toward the curb by the impact. Both of his shoes flew off, one landing in the center of the street and the other in front of his apartment. By the time the police arrived, he had no pulse.

A passer-by placed the first 911 call. Ms. Menendez called the police four minutes after the crash, telling a 911 dispatcher that Mr. Koop had jumped onto her car, an explanation she repeated to a Bogota officer investigating the crash.

A man who arrived soon after the crash on Ms. Menendez’s behalf identified himself as a retired member of the police department in Hackensack, a neighboring city. He can be heard on a dashcam video inquiring about the investigation and whether the police planned to involve the Bergen County Prosecutor’s office.

Mr. Koop’s death has been the only motor-vehicle fatality in Bogota, a small suburban borough of about 8,000 people near the Hackensack River, since 2018, according to state data. It was one of 19 pedestrian fatalities in Bergen County in 2018, a figure that has fluctuated only slightly in recent years, according to state data. Driving while intoxicated was a factor in nearly one-third of the 524 fatal car crashes in New Jersey that year.

Police officers, who must have probable cause to test a driver for alcohol, did not test Ms. Menendez, even though days after the crash, police investigators still sought to prove Mr. Koop had been drinking that night.

State records show that a majority of surviving drivers involved in fatal crashes are not tested for alcohol. Only 30 percent of surviving drivers were tested in 2018, while most pedestrians killed, 154 out of 175, were tested for alcohol, presumably through autopsies.

Also on Thursday, in a sign of the complicated and interwoven nature of the charges Mr. Menendez faces, a federal judge rejected a guilty plea that one of the senator’s co-defendants made over a year ago in an unrelated bank fraud case.

Fred Daibes, a New Jersey developer who was accused last month of giving the senator and his wife bribes, had pleaded guilty to making false entries in connection with a loan document. The $1.8 million loan was paid back, and the plea agreement, approved by prosecutors in the U.S. attorney’s office in New Jersey, did not call for prison time.

But on Thursday, Judge Susan D. Wigenton of U.S. District Court in New Jersey summarily rejected Mr. Daibes’s plea.

“The court is not required to adhere to the terms of the plea agreements,” the order by Judge Wigenton states, “and the cases may be disposed of less favorably toward the defendants than the plea agreements contemplated.”

The new indictment alleges that Mr. Menendez tried to install a political ally as U.S. attorney in New Jersey in an effort to help Mr. Daibes get off easy in the bank fraud case. The ally, Philip R. Sellinger, was appointed to the position, but recused himself from the investigation involving Mr. Daibes.

A spokesman for Mr. Sellinger has said that “all activity by the office related to that matter was handled appropriately according to the principles of federal prosecution.”

Lawrence S. Lustberg, Mr. Daibes’s lawyer in the bank loan case, said he and his client were “carefully evaluating our options as a result of the court’s order.”

Kirsten Noyes contributed research.