Federal investigators are expected to announce a review of the North Charleston (SC) Police Department Tuesday, according to a U.S. Justice Department news release.

The mayor and police chief in the city of 100,000 requested the review, saying the scrutiny stemming from the police shooting of Walter Scott had made its efforts to protect residents while respecting their rights "more urgent and challenging."

"Trust and communication are essential for improvement, and, as you can imagine, the death of Walter Scott damaged trust and made communication more difficult," the letter said. "Our efforts have uncovered some areas in which we could benefit from outside assistance. We hope that your office may now be in a position to facilitate that."

Word that the Justice Department will conduct a review comes 13 months after former Officer Michael Slager fatally shot Walter Scott following an April 2015 traffic stop. Video of the incident showed Slager shooting at Scott.

Slager was charged with murder shortly after the shooting. The police department then fired him, and a grand jury indicted him on the murder charge. Last week, a federal grand jury handed down an indictment for a civil rights violation.

Slager has pleaded not guilty to both the local and federal charges. His defense team has said he shot Scott after the two tussled over Slager's Taser, CNN reports.