(CNN) The Chicago police union is again calling for a federal investigation into State's Attorney Kim Foxx to determine the extent of her involvement with the Jussie Smollett case.

Kevin Graham, president of the Chicago Fraternal Order of Police, said the demand is based on news reports about text messages between Foxx and an attorney about, according to him, "diverting the case from Chicago police department to a federal investigation."

Foxx, the state's attorney for Cook County, recused herself from the Smollett investigation in mid-February. She told CNN affiliate WLS on Wednesday that she did so when it was clear Smollett's role in the case was changing from victim to suspect.

She told the Chicago station she did so after consulting with her department's chief ethics officer.

Smollett was charged about a week later with 16 counts of filing a false police report, a Class 4 felony. Foxx said she was never actively involved in the case because the crime was the lowest level of felony, but she did get updates until an email from the chief ethics officer went out to her staff, instructing them not to include her in discussions about the investigation.

Read More