Federal prosecutors have launched a probe into the NYPD’s Special Victims Division, looking into whether the embattled sex crimes unit engaged in a “pattern or practice” of gender-biased policing, it was revealed Thursday.

Investigators will probe reported systemic issues with the division in the nation’s largest police force, which have been ongoing for more than a decade, the Department of Justice said in a press release.

“The Department received information alleging deficiencies at SVD that have persisted for more than a decade, depriving survivors and the public of the prompt, thorough, and effective investigations needed to protect public safety,” officials said.

“These deficiencies allegedly include failing to conduct basic investigative steps and instead shaming and abusing survivors and re-traumatizing them during investigations,” they added.

The investigation comes nearly a year after more than a dozen New York sexual assault survivors penned a letter to DOJ requesting it investigate the embattled division. 

“Because we wanted to protect others from the kinds of harm we suffered, as well as to seek justice for ourselves, we reported our assaults to the NYPD,” read the letter, signed by 19 people. 

“We expected that the well-funded, technologically sophisticated police agency of the nation’s largest city would respond to our assaults with professionalism and with thorough, skillful, truth-seeking investigations,” the letter states.

“What we experienced was the opposite.” 

One of the letter’s signatories, rape survivor Leslie McFadden, was elated by the news when reached by The Post Thursday. 

“I’m a little speechless at the moment but that’s incredible. That’s what we asked for. It’s a very first step. It’s not quite the victory yet but it’s definitely a joyous moment,” she said.

McFadden, who alleges she was tricked by an SVD detective into closing a complaint against her attacker, said last year that, “From the very beginning, I was lied to, I was dismissed. … It has been a gut punch to deal with [the NYPD].”

Jane Manning, a former sex crimes prosecutor who helped organize the letter last year, told The Post Thursday that the investigation is a “victory” for sex crime survivors. 

“Today the Justice Department is weighing in on the side of equal protection for survivors of sexual assault. This is a victory for survivors, for women and for the fair administration of justice. Most of all, this is a victory for the brave survivors who spoke out about their abysmal mistreatment by the NYPD,” she said. 

NYPD Deputy Chief Michael Osgood, who claims he was unfairly forced out as commanding officer of the division last year, told The Post Thursday that he hopes the investigation will fix the systemic issues within SVD.

“What has to be accomplished here is the correction of the severe structural deficiencies at the Special Victims Division. That includes cases that are diluted, victims being mistreated, investigative steps being half-completed and damage being done by the compstat process,” Osgood said. 

“The hope is that the department of justice discovers and forces the city of New York to fix the external systemic factors that are the root cause of the substandard investigative work inside special victims,” he added.

Sexual assault victim Desdemona Dallas Meck, who uses gender-neutral pronouns, said they were interviewed by Justice Department investigators months ago about SVD’s handling of their case over the course of nearly a decade. 

“I hope that this can be a more widespread investigation around how institutions like the NYPD are treating survivors and hopefully if there’s federal recognition of that there can be regulations and laws put into place so that survivors are believed on a more constant basis,” Meck told The Post. 

If the investigation uncovers systemic issues at SVD, the feds will be able to provide oversight to the department to ensure they’re remedied. If reforms are still not made, they’ll be able to file suit against the department to enforce changes.

The probe will be jointly conducted by investigators from the Southern and Eastern districts of New York, as well as the Special Litigation Section of the Justice Department’s Civil Rights Division.

“Victims of sex crimes deserve the same rigorous and unbiased investigations of their cases that the NYPD affords to other categories of crime,” Damian Williams, the US attorney for the Southern District, said in a statement.

“Over the last several months, we have learned concerning information from a variety of sources of historical issues about the way the Special Victims Division has conducted its investigations for many years,” added Breon Peace, the US attorney for the Eastern District.

In a statement, an NYPD spokesperson said the department, “welcomes the review by the U.S. Department of Justice.”

“As an agency, we have committed to improving the quality of our investigations and the care provided by the Special Victims Division when working with some of the most vulnerable survivors of crime,” the statement said.