After decades on the job, they had plenty of reasons to like working for the New Jersey State Police.

Dawn Curran, 53, was proud to be among an elite cadre of troopers selected to protect the state’s governors. Wanda Stojanov, also 53, believed in showing her daughters that women could excel in male-dominated careers. For Rebecca Hotchkin, 56, the job offered meaningful work, competitive pay and health care that helped save her life when she got cancer.

But if a sister, daughter or niece wanted to join New Jersey’s largest and most prestigious policing agency, each woman said she would offer the same advice: Don’t.

“Run the other way,” Ms. Hotchkin said.

The New Jersey State Police employed 174 female officers last year — just 5.6 percent of its 3,117 troopers. That’s less than the national average for comparable state police departments, and less than half the average for all policing agencies, according to Justice Department data.

Before retiring in the last year, the three women joined with a female trooper who is still on the force, Claire Krauchuk, to file a lawsuit that accuses the department of gender bias so entrenched that it often keeps women from being promoted to top command posts.

Their suit echoes similar claims of discrimination made in recent years by other women and by gay, Black and Latino officers employed by the State Police, an agency controlled by Gov. Philip D. Murphy, a Democrat, and one of his closest allies, Matthew J. Platkin, the attorney general.

Their allegations have now drawn the scrutiny of the U.S. Justice Department.

Federal officials traveled from Washington in late September to meet with the U.S. attorney for New Jersey, Philip R. Sellinger, and more than a dozen former troopers, lawyers and civil rights leaders in Camden, N.J.

Justice Department officials declined to comment on the meeting or the inquiry, but have since requested documents and conducted additional interviews, according to four people at the meeting.

“They are investigating, and we are hopeful,” said Gregg L. Zeff, a civil rights lawyer for the N.A.A.C.P. New Jersey State Conference who attended the two-hour meeting.

“The department has always had a cultlike behavior and following,” he added. “You’re either in or you’re out — and it’s very difficult to get in.”

The State Police refused requests for information about employment data, promotion policies or the specific claims laid out by the women and more than 20 other plaintiffs in recent lawsuits; it has referred all questions to the attorney general’s office.

Past attempts by the State Police to increase gender diversity, and the department’s history of racial tension, are well documented.

In 1980, it graduated the country’s first all-female class of cadets in an overt effort to diversify its ranks.

The department has made strides toward racial diversity, but three of every four of its troopers are white, in a state that is among the most ethnically diverse in the Northeast. It has been subject to two federal consent decrees, including one that lasted 10 years because of a documented pattern of racial profiling in highway traffic stops.

In March, Major Brian Polite, one of the department’s highest-ranking Black officers with more than 20 years of experience, filed a lawsuit that claimed he was passed over for a promotion and was the subject of racist remarks by colleagues.

During Mr. Murphy’s first term as governor, the attorney general’s office hired a national law firm, Kaufman Dolowich, to look into persistent claims of both gender and racial discrimination in State Police employment practices.

Between September 2020 and June 2023, New Jersey paid the firm $478,128, records show, but officials in the Murphy administration say that the assessment is not yet complete. A lawyer who was leading the inquiry, Karol Corbin Walker, did not return calls or emails.

“The review of the hiring and promotional practices of the New Jersey State Police remains underway,” a spokeswoman for Mr. Platkin said in an email. “Upon the completion of the review, the Office of the Attorney General will make public the findings.”

State Police employees are discouraged and in some cases barred from speaking publicly about concerns identified in lawsuits.

But as recent retirees, Ms. Curran, Ms. Stojanov and Ms. Hotchkin are under no similar strictures. Each said she never wanted to file suit.

“In the back of your mind, you keep saying, ‘All right, they’ll do the right thing next time,’ or, you know, ‘I’ll get the next promotion,’” said Ms. Hotchkin, who retired as a lieutenant. “And you just wait and wait and it never happens.”

The women’s suit asserts broad, yearslong claims of a hostile work environment and a culture dominated by straight white men with unfettered power to promote their friends.

Ms. Stojanov’s promotion to major, after nearly 27 years of decorated service, came after she said she was barred from interviewing for 25 top command spots.

Ms. Curran described a series of arbitrary job assignments and being passed over for more desirable posts in favor of male officers with less experience.

Ms. Hotchkin, undergoing treatment for breast cancer and on a temporary leave, was told that her absence was holding up promotional decisions, court records show. She eventually had an in-person interview and earned the highest score. But the job went to a man.

Ms. Krauchuk’s claim centers on the hurdles she encountered while undergoing fertility treatments and after the birth of her two children. She said she was forced to pump breast milk in squad cars, storage closets and the soiled bathroom of a trailer and was then reassigned and subjected to disciplinary action after an incident involving the governor’s wife, Tammy Murphy, according to the lawsuit.

Ms. Murphy refused a request to allow Ms. Krauchuk, who was assigned to protect her, to pump milk in a carriage house at the family’s private home because of the “optics,” the suit charges. Ms. Murphy, who is now running for U.S. Senate, did not address the specific claim, but said that “any characterization” that she would not be supportive of breastfeeding or pumping was “categorically false.”

The disciplinary charges against Ms. Krauchuk were recently dismissed, her lawyer, Michelle J. Douglass, said.

The women’s lawsuit, filed in December 2021 and amended in May, seeks compensation for lost opportunity wages, new policies that set objective standards for promotion and the creation of sanitary locations where breastfeeding troopers can express milk, among other requests.

Over the past six months, the retired troopers have also become something they never envisioned: activists.

They have met with national women’s organizations and in July joined with a group of civil rights leaders to ask the federal government to intervene at the State Police — a request that led to the September meeting. They even sought guidance from Lilly Ledbetter, whose lawsuit against Goodyear Tire paved the way for the 2009 federal equal-pay law.

“We’re never going to stop the cycle,” Ms. Stojanov said, “if we don’t speak up.”

In 2019, a nationwide effort to increase the ranks of female police officers gained key backing from the Justice Department and a name — “30 by 30.” Its goal is for women to comprise 30 percent of new police recruits by 2030. (Women made up roughly 12.3 percent of new recruits in 2018, the most recent nationwide data available.)

The initiative drew little notice at first, with only about 34 agencies signing the pledge to work toward the goal.

Then, as protests over the 2020 police killing of George Floyd swept the nation, interest surged, buoyed by demands for a new approach toward criminal justice.

About 340 agencies — including the police departments in New York City and Los Angeles and the State Police in New York and Massachusetts — have now publicly committed to adopting the program’s goals and complying with its mechanisms for monitoring progress.

The 30-by-30 initiative was founded by Maureen Quinn McGough, then a senior policy adviser at the National Institute of Justice, and Ivonne Roman, a retired New Jersey police captain whose assignments during her quarter-century career included gang and drug squads and five months as Newark’s chief of police.

Their effort is based on decades of research that shows that women police officers use force less frequently than men, are the target of fewer civilian complaints and make fewer discretionary arrests, especially of nonwhite residents.

“Women have been de-escalating before there was a term ‘de-escalation,’” Ms. Roman said. “If I can calm down a situation and get it resolved without effecting an arrest, why wouldn’t I do that?”

New York State has managed to attract and retain an above-average number of women to its statewide force. In 2018, it employed 10.5 percent female officers, well above the 6.9 percent national average for comparable statewide departments, federal data show. New Jersey’s rate that year was 4.8 percent.

Alex Piquero, a former director of the Bureau of Justice Statistics in Washington who now teaches criminology at the University of Miami, said the gaps posed crucial questions for New Jersey leaders.

“If the barometer is the national average, why are we lower? And why are we lower right next to a state that is doing far better?” Professor Piquero said.

Ms. Curran, whose father retired from the State Police in 1992, said she was originally hopeful that women could work for change from within the organization. She said she sat down with Mr. Murphy’s former chief of staff in 2020 to discuss her concerns.

Focus group meetings were later scheduled to try to address anonymous letters female troopers had sent to a former attorney general about the agency’s low number of women officers.

Colonel Patrick J. Callahan, the top executive at the State Police, attended one of the online-only sessions. But Colonel Callahan, who declined interview requests, said he could not attend an in-person meeting at the State Police campus in Ewing, N.J., because of a “previous engagement,” according to a court filing.

During the meeting, in a building with a large window that overlooks the campus, Colonel Callahan was spotted going for a jog with his longtime assistant, court records show.

“People stood up and pointed,” said Ms. Curran, who was in attendance.

“It was insulting,” she added. “But — and I don’t know how else to say this — we were kind of used to being insulted.”

The meeting ended abruptly.