HOUSTON, Texas — A 20-year-old Houston man was federally indicted in connection with the armed robbery of mail carriers, the U.S. Attorney's Office of the Southern District of Texas announced Monday.

A federal grand jury returned an indictment against 20-year-old Xzavier Ivar Shephard earlier this month on charges for aiding and abetting interference with commerce by robbery.

Shephard made his initial appearance in federal court on Monday.

"Originally charged by criminal complaint, Shephard was believed to be involved in at least four armed robberies of postal letter carriers since June," read a statement from the U.S. Attorney's Office.

"The charges allege a young male would approach letter carriers while engaged in the performance of their duties. He would allegedly display a gun and/or threaten force and make demands for certain items."

According to the charges, the alleged robbery suspects would then flee in a black Buick vehicle with paper plates, which were registered to Shephard.

The robberies occurred on June 24, June 29, and twice on September 25, according to the criminal complaint.

If convicted, Shephard faces up to 25 years in federal prison as well as a mandatory minimum of seven years that must be served consecutively to any other prison term imposed.