According to the government, in January 2020, a Black employee found a hangman’s noose at his worksite at the Baton Rouge complex run by Exxon Mobil Corp. and reported it. At the time, the company knew of three other nooses that had been found at the complex, but it failed to investigate all the complaints and take action to prevent such harassment, the U.S. Equal Employment Opportunity Commission said in its lawsuit filed Thursday.

Then, in December 2020, a fifth noose was found at the complex, which includes a chemical plant and nearby refinery. Exxon Mobil’s lack of action created a racially hostile work environment, the EEOC said.

Todd Spitler, a spokesperson for Exxon Mobil, said in a statement Sunday that the company disagrees with the EEOC’s allegations and that it “encourage(s) employees to report claims like this, and we thoroughly investigated.”

“The symbols of hate are unacceptable, offensive, and in violation of our corporate policies,” Spitler said. “We have a zero tolerance policy of any form of harassment or discrimination in the workplace by or towards employees, contractors, suppliers or customers.”

Employers who become aware of racially offensive or threatening conduct in the workplace are legally obligated to take “prompt, remedial action aimed at stopping it,” Rudy Sustaita, an attorney at the EEOC’s Houston district office, said in a statement.

Elizabeth Owen, a senior trial attorney in the EEOC’s New Orleans field office, said in a statement that the displays of nooses required swift action.

“A noose is a longstanding symbol of violence associated with the lynching of African Americans,” she said. “Such symbols are inherently threatening and significantly alter the workplace environment for Black Americans.”

In 2021, eight nooses were found at an Amazon warehouse construction site in Connecticut. Amazon had briefly closed the site after the seventh one appeared.