The Mississippi Bureau of Investigation already is handling the case of Dominique Clayton, who was found dead last week.
Matthew Kinne, a former Oxford officer allegedly involved in a relationship with Clayton, has been charged with murder. Kinne was terminated as an employee by the city May 21, and the police department's interim chief said at a court hearing that the department stood with the victim's family.
Tannehill confirmed Tuesday that she called Attorney General Jim Hood's office last Friday on behalf of the city.
"These two entities will complete thorough investigations with the full cooperation and support of the Oxford Police Department and City of Oxford," Tannehill said, expressing her remorse to Clayton's family.
"Our community continues to mourn alongside the Clayton family," she said. "Dominique Clayton was a mother, daughter, sister and friend and I simply cannot imagine the pain her family is dealing with right now. We extend our deepest sympathies to Dominique’s family and friends. It is my prayer that this tragedy will unite us as a community."
Tannehill also said that the mayor and Board of Aldermen have not suspended or terminated any other officers, aside from Kinne.
Carlos Moore, attorney for the Clayton family, said he has spoken to Hood's office regarding the investigation.
"I appreciate the mayor calling his office in to investigate," Moore said.