William Barr, a former U.S. attorney general under President George H.W. Bush, has returned to Kirkland & Ellis as of counsel in Washington, D.C. The news was not announced by Kirkland, but by Caterpillar Inc., which recently hired Barr and the firm to advise it in an investigation.

Crain’s Chicago Business reported Thursday that Barr and Kirkland had been retained to represent the Peoria, Illinois-based company in the aftermath of a raid by federal law enforcement officials on three of its offices in the state earlier this month.