The Department of Justice (DOJ) issued a fine to the Denver Sheriff Department after a federal investigation found it incorrectly listed being a US citizen as a job requirement during a major hiring spree.

From January to March 2015, the police department, which is the largest sheriff department in Colorado, went on a recruitment drive, hiring more than 200 deputies to the team, but only US citizens were able to apply, which the DOJ ruled as unlawful.

Justice Department Settles Immigration-Related Discrimination Claim Against the Denver Sheriff Department https://t.co/UsTovKEkuo — Justice Department (@TheJusticeDept) November 21, 2016

Along with a $10,000 fine, the department will also have to rexamine all job applications in the last two years and identify immigrants who applied for roles but were excluded because of their status.

US police spend millions on social media monitoring tools, study finds https://t.co/Bn1ndsDA8Cpic.twitter.com/MW9ojWt4ya — RT (@RT_com) November 19, 2016

In a statement, the Justice Department said the police department “discriminated based on citizenship status” and violated the Immigration and Nationality Act.

“We commend the Denver Sheriff Department for its cooperation and commitment to removing unnecessary and unlawful employment barriers,” Principal Deputy Assistant Attorney General Vanita Gupta said.

“Eliminating this unlawful citizenship requirement will help ensure that the Denver Sheriff Department hires the best and most qualified individuals to protect and serve. The entire community will benefit from these reforms.”

READ MORE: Respect for police among Americans surges to highs not seen since late '60s

Under the Immigration and Nationality Act, citizenship, immigration status and national origin cannot be used in discriminating against individuals in relation to hiring, firing or recruitment.

All employers are obliged to equally treat those who are non-citizens but have valid work permits, unless state, local or federal law specifically requires certain jobs to only be open to US citizens.