Officer Cleon Brown said he took a genetic test through Ancestry.com, which revealed he was 18 percent African.
The discrimination began, he alleges, when he shared the result with his colleagues at the police department in Hastings, Michigan
Brown's police chief referred to him as "Kunta," the lawsuit says. (Kunta Kinte is a character in Alex Haley's novel, "Roots: The Saga of an American Family.")
Co-workers started whispering "Black Lives Matter" while pumping their fists as they walked past him, he claims.
CNN was unable to reach Brown. But Brown told CNN affiliate WDIV
, "It was almost like a disgraced type of reaction that I got from them like, 'Why are you proud of this type of thing?'"
Veteran officer vs.city
Brown is a sergeant at Hastings PD and has been with the department for 19 years.
In 2016, he took the Ancestry.com test and "proudly told other Hastings employees of the test and result," his suit says.
The series of taunts began soon afterward, he says. The police chief, fellow officers and the former mayor allegedly used derogatory remarks about his race.
"It's very hurtful, I was so, so upset and still upset about it," Brown told the affiliate.
The city's version of events is different.
In a statement to CNN, it said that Brown, on many occasions, made "derogatory, inappropriate, insensitive,and rude comments about African-Americans.
The city statement also said Brown "joked" about the results of the genetic test with colleagues:
"Other officers have stated that after Brown first told them about the test results they never approached him about it again. Instead, it was Brown who specifically went to other officers, raised the topic, joked about it, and engaged in typical racial stereotypes. Clearly, Sgt. Brown welcomed his interaction with other officers on this topic."
As is the case in many lawsuits, the two sides disagree about the contentions.
"My client never joked about his race/origin. He is very proud of it," Brown's lawyer, Karie Boyland, told CNN. "Nothing to joke about."
The Santa head
Around Christmas 2016, someone placed a black Santa head in his Christmas stocking. It had "18%" written on its beard, the suit says.
"I call it straight up racism," Brown told the affiliate.
The city rebuts the officer's claims.
"During this most recent holiday season, a good friend of Brown found a tan color ceramic Santa head sitting in his own stocking with "18%" written on it. Not knowing where it came from and knowing his friendship with Brown, the officer placed it in Brown's stocking," the city statement said.
It goes on to say: "The officer who placed the Santa in Brown's stocking then went to Brown to apologize for doing so, since he head that Brown was upset about the incident."
Brown's lawyer doesn't buy that explanation.
"It's a manufactured defense, but what else can they say?" she said.
The lawsuit says Brown has suffered stress at work which has led to health complications. He is asking for half a million dollars.