A Brooklyn assistant district attorney has been arrested on charges of eavesdropping after she allegedly forged documents in order to spy on a love interest who is an NYPD detective, sources said.

Tara Lenich, 41, who headed the Violent Criminal Enterprises Bureau, surrendered early Monday to her own district attorney’s office on charges related to wiretapping conversations between the cop and another woman, according to the sources.

A prosecutor — and former colleague — at her arraignment Monday night called Lenich’s alleged actions a “stunning betrayal to her oath of office and the justice system that we uphold.”

Lenich was charged with eavesdropping and criminal possession of a forged instrument for allegedly using forged warrants to tap two cellphones.

The papers were forged on 20 occasions with various judges’ names, and the scheme went on for an entire year, prosecutors said.

It was unclear what the relationship was between Lenich and the detective, but sources said there was a romantic connection at one point and she may have been a spurned lover.

The woman who was allegedly wiretapped may have been the detective’s new love interest, sources said.

The unidentified cop was placed on modified duty when he was allegedly caught threatening Lenich on the illegal wiretap, according to the sources.

Acting Brooklyn District Attorney Eric Gonzalez said his office took action to make sure it was an isolated incident.

“As soon as these allegations were uncovered, we conducted a swift and thorough investigation, immediately terminating the employee, and ordered a complete review of our protocols and proceeded to make sure that this abuse of authority never happens again,” said his spokesman, Oren Yaniv.

Lenich’s lawyer said his client “enjoys the presumption of innocence.” She was released on $25,000 bond.

FBI agents were executing a search warrant at Lenich’s Manhattan apartment Monday night.