Montana's chief federal judge will retire following an inquiry into an email he forwarded that included a racist joke involving President Barack Obama.

A statement posted Tuesday on the 9th U.S. Circuit Court of Appeals' website says U.S. District Judge Richard Cebull submitted a retirement letter effective May 3.

The Billings judge previously announced he would take a reduced caseload and step down as the chief judge. But Cebull signaled his intention to fully retire after a judicial council issued a March 15 order following the investigation into the email.

The court's statement says the council's order is confidential during an appeal period.

Cebull and another group requested an investigation after the contents of the February 2012 email were published by The Great Falls Tribune. You can see the email below.