After 13 University of North Carolina football players were suspended for selling team-issued Air Jordans earlier this week, several other Jordan Brand outfitted schools are investigating violations involving their own athletes.

ESPN reports that Michigan, Marquette and Cal are also looking into the matter after being alerted by UNC officials. Team-issued Jordans fetch thousands of dollars on the open market, often moved through consignment shops and digital marketplaces.

Air Jordan 32 Marquette PE Right
Image via marquette.basketball

According to Michigan football spokesman Dave Ablauf, the school's players sign a form acknowledging that selling the shoes could jeopardize their eligibility. Additionally, the shoes are marked by equipment staff with the player's name or uniform number, enhancing the difficulty of selling them anonymously. Marquette spokesman Mike Broeker says the school will now stipulate that players wear the shoes multiple times, likely decreasing and making them less tempting to sell. The school is also stitching player numbers into the shoes.

Known for its exclusive apparel and footwear, the University of Oregon issues its exclusive Jordans to be worn for travel and certain events, but the equipment staff collects and stores them immediately afterward in trunks. Players get all of their pairs back when their eligibility expires.

It's worth noting that team-issued Air Jordans are sometimes gifted to celebrities, executives, alumni and contest winners, so not every pair that hits the open market is guaranteed to have been sold by a student. As of now, none of the three schools have announced violations.