Henderson led the Rebels to a 27-9 record last season, including their first NCAA appearance in a decade and an SEC tournament championship. He finished as the leading scorer in the SEC with 20.1 points per game, and was named SEC tournament MVP.
Henderson's suspension stems from a failed drug test, according to Gary Parrish of CBSSports.com, citing a source.
"Since the season ended, we have talked a lot about Marshall taking a greater leadership role with our team," head coach Andy Kennedy said in a school release. "With that comes greater responsibility, and he must do a better job of living up to the high standard we expect from him and he desires from himself."
Henderson, who started 33 games in 2012-13 and set the NCAA single-season record for 3-point attempts (394), as well as the SEC mark for 3s made in a season with 141, was known as much for his flamboyant on-the-court behavior as his prolific scoring ability.
In an open letter to Ole Miss fans in April, Henderson not only announced his intentions to return for his senior season, but took responsibility for those times when his passion for the game "boils over," most notably following the Rebels' third-round loss to La Salle in the NCAA tournament, when he extended both middle fingers to the crowd as he exited the playing court.
"He's very grateful for the opportunity; he understands the opportunity he's been given here," Kennedy said in a previous interview with the Ole Miss Spirit. "He understands the appreciation that the Ole Miss nation has give him. He wanted to do it. It was his idea to come out and basically man up and own some of the things he's done.
"He's done so many good things for us between the lines; he brought a lot of publicity to our program and he certainly helped us win a number of games, including an SEC championship. But he also knows he did some things he shouldn't have done, that did not reflect the right light on him, the program or the university. I give him a lot of credit. The letter shows he's continuing to mature as a young man, and I know this off-season he'll continue to put in the work necessary to continue to mature as a basketball player."
Henderson arrived at Ole Miss a year ago with a checkered past, which included an arrest on forgery charges and a failed drug test in January 2012, requiring Henderson to serve jail time.
He played one season at Utah, where he started 30 games as a true freshman. He earned All-Mountain West honorable mention after finishing second on the team with an average of 11.8 points per game. He led the Utes with 13.6 points during conference play.
Even then, he was making waves for the way he acted. He was suspended one game for his involvement in an altercation at BYU.
He transferred after one season, opting for Texas Tech. He sat out the 2010-11 season, never played a minute, and transferred to South Plains at the end of the season. He earned NJCAA first team All-America honors in leading the Texans to a perfect 36-0 record and junior college national championship.
But he had his troubles there, too, most notably a probation violation.