Mark G. Wessel, dean of the H. John Heinz III School of Public Policy at Carnegie Mellon University, has abruptly resigned after an investigation into a degree awarded there in 2004, the year he became permanent dean.

The Pittsburgh Post-Gazette reported today that Mr. Wessel stepped down last week as a result of what the school described as “an error in judgment” involving “the approval of excessive transfer credits and excessive units for independent study in lieu of course work” in the awarding of a master’s degree in 2004.

Citing privacy laws, university officials did not release the name of the degree recipient. They are investigating whether other degrees were improperly awarded as well.

Mr. Wessel was an economist and financial analyst for the U.S. Department of Energy before joining the Heinz school, in 1993. He served in multiple administrative positions at the school, including as chief operating officer, before becoming dean, in 2004. —Richard Byrne