The former police chief of Portsmouth, Va., says she was forced out by city leaders over resistance to her attempts to overhaul a department riven by racial tension.

Tonya Chapman, who previously worked on police forces in Arlington and Richmond, was the first black woman to lead a municipal police department in Virginia until her resignation last week. In a statement Monday, she said that before arriving in Portsmouth in early 2016, she had “never witnessed the degree of systemic bias and acts of systemic racism, discriminatory practices and abuse of authority in all of my almost 30 year career in law enforcement and public safety.”

Chapman said she came to Portsmouth aware of “external strife” between police and residents in the majority-black coastal city, particularly in the wake of the fatal shooting of an unarmed black teenager by a white officer in 2015. But she said it was the officer’s conviction on manslaughter charges the following year that revealed to her the depth of “racial tensions within the police department” as well.

Some of what she observed, she said, is “so inflammatory” that she would not detail it in her letter “out of concern for public safety.” But she said she would share specific information with appropriate government agencies.

Most officers, she said, welcomed her efforts to “change this culture.” But a contingent did not, she said, including members of the influential police union that had been disciplined for policy violations.

“There were officers in the department who . . . did not want me to hold them accountable for their actions,” she wrote. “Some quite frankly did not like taking direction from an African American female.”

In her letter, Chapman touted her accomplishments, including an increase in female and minority representation in the department. She also introduced body cameras and launched community engagement initiatives.

James Boyd, president of Portsmouth’s NAACP chapter, said Chapman “is a victim of a severe system of racism inside the Portsmouth Police Department, inside the governing structure of the city as a whole.”

As Chapman did in her letter, he said he believed politically connected members of law enforcement put pressure on the city council to have her removed.

“We didn’t always see eye to eye,” he said. “We had some issues. We thought reforms could have gone a lot faster. But progress was being made.”

The Portsmouth Fraternal Order of Police did not immediately return a request for comment. Last summer, when Chapman emailed the department to criticize “a few toxic employees,” FOP President Matt Crutcher called the message “a personal attack” on some.

Chapman was not always at odds with the union. She stood by an officer who shot a burglary suspect in 2017, making him officer of the month for his “heroic response.” That officer is set to go to trial on felony charges this year.

She has been replaced in the interim by her deputy, Angela Greene. A spokeswoman for the police department declined to comment on Chapman’s allegations. City Manager Lydia Pettis Patton, who Chapman said told her to resign or face termination, did not return a request for comment.