(CNN) A group of police officers in Montgomery County, Maryland, are being accused of repeatedly making hateful comments against people of color in a group text message chain -- including that they hoped Black Lives Matter protesters would die.
One of their colleagues, Mark Miles, filed a lawsuit this week claiming his supervisor at the Maryland-National Capital Park Police and other officers sent the text messages in a chain meant to discuss work assignments. They also "mocked, demeaned, ostracized and humiliated" him for being Black, according to the lawsuit.
Miles' unit patrolled parks, primarily those in Montgomery County.
The lawsuit, which was filed Monday in the US District Court for the District of Maryland, accuses the Maryland-National Capital Park and Planning Commission and Stephanie Harvey, his supervisor in her official capacity, of harassment, discrimination and retaliation.
The agency manages parks and planning in Montgomery and Prince George's counties.
When Miles, who joined the park police in 2019, started working in Harvey's unit in 2020, he realized it was "common practice" for the unit to make offensive comments about people who are not White, including himself, the lawsuit says.
More than a dozen text messages are described in the lawsuit as examples. They include offensive comments about Black, Asian, Jewish and Hispanic people as well anti-LGBTQ remarks.
When the officers discussed Black Lives Matter protesters, Harvey texted it was "time to start killing" and "Well they got the Army out there sooooo ... hopefully they will get to kill some people," and, "Kill em all," according to the lawsuit.
In the months after the 2020 murder of George Floyd by a White police officer in Minneapolis and the protests that followed, Harvey complained about the department's position on Black Lives Matter protests and said the agency should not support protesters, the lawsuit says.
Harvey also referred to Miles as "colored" during a roll call meeting on August 4, 2020, the document states.
Another text message appears to indicate that Harvey was aware her comments made in the group chat were offensive. "Joke, don't turn these texts over to [Internal Affairs] and get me fired for hate speech!," she wrote in a text message, according to the lawsuit.
CNN has reached out to Martin Oliverio, a lawyer who represents Harvey, but has has not received a response.
In a statement, the Maryland-National Capital Park Police said the agency launched an investigation when the series of text messages came to their attention but did not specify when that took place.
The lawsuit states Miles first reported Harvey's behavior to a captain on August 2020, "continued harassment and retaliation" by Harvey and other officers to Internal Affairs on February 2021 and to the Equal Employment Opportunity Commission on March 2021.
Several officers were suspended and referred to the disciplinary process for termination, the Maryland-National Capital Park Police said, adding that it could not discuss further details on the employment status of the officers involved in the text messages.
But the lawsuit notes Harvey was suspended in March 2021 and some of the other officers were promoted since Miles filed his complaints.
The department declined to share details about the disciplinary actions taken and said "the suggestion that Park Police management ignored allegations of misconduct by this group of officers is simply incorrect, and we will make the results of the trial board process public at the appropriate time."
"Our Park Police leadership team does not tolerate racism or harassment in the workplace and will not hesitate to put a stop to any such behavior whenever it arises," the park police added.
Jay Holland, one of the attorneys representing Miles, said there is a "toxic culture" within the police department and the work environment that his client endured was horrific.
"A culture where racism and bigotry is the norm cannot be allowed to stand," Holland said. "Officer Miles has been further victimized by his fellow officers and the department for bravely coming forward. After coming forward, he was ostracized by his colleagues, moved to a night shift and he fears for his safety."
The Fraternal Order of Police Lodge 30, the union representing active and retired officers of the Maryland-National Capital Park Police, declined to comment on the lawsuit.
But the union said in a statement that it "works tirelessly to see that all members are treated fairly, have the best possible work environment and are afforded their due process rights as defined by law."
Miles faced pressure to leave the unit after he made complaints about the harassment, and ultimately "involuntarily transferred to another, less desirable night shift," last November, the lawsuit says.
Attorneys for Miles filed the lawsuit after the Department of Justice issued a right-to-sue letter earlier this month in connection with his complaint to the Equal Employment Opportunity Commission.
He is seeking economic and compensatory damages, a judge order to ensure park police refrain from retaliating against him, the appointment of an independent monitor to ensure compliance of the court's decision, punitive damages against Harvey and the termination of her employment.
"I think this is really indicative of the larger issue of racism that is endemic in policing today," said Erika Jacobsen White, another of Miles' attorneys. "The natural outgrowth of this type of overt and systemic racist mentality in policing is what leads to the kind of police abuses we are seeing across the country."