Jesse Ryan Loskarn, 35, the chief of staff of the office of U.S. Senator Lamar Alexander was arrested on probable cause of the charges by the U.S. Postal Inspection Service. Loskarn was held pending an expected Thursday court hearing.
Loskarn's home was searched during the investigation.
Alexander placed Loskarn on unpaid leave. Alexander said his office was fully cooperating with investigators. Loskarn has served as chief of staff for Alexander for two years.
Alexander is a former Tennessee governor and has also served as the U.S. Secretary of Education. He was first elected to the Senate in 2002.
According to Loskarn's biography on his LinkedIn account and in previous communications for Alexander's office, Loskarn graduated from Tulane University in 2000 and went to work for retired Republican U.S. Rep. Wally Herger of California as a legal assistant. He later was the communications director for U.S. Rep. Marsha Blackburn, a Tennessee Republican, and eventually became staff director for the Senate Republican Conference.
The Associated Press contributed to this report.