The Allegheny County medical examiner's office in Pittsburgh said that Johnson died of a self-inflicted gunshot wound, reports the Associated Press.
Johnson, who was found Saturday, played for the Gators for two seasons and was often featured on special teams plays. He recorded 19 tackles across the 2011 and 2012 seasons with Florida.
He was ejected from his final game as a Gator, the 2013 Sugar Bowl, after throwing a punch following a surprise onside kick from the opposing Louisville Cardinal squad. Johnson transferred from Florida to Duquesne shortly after the incident.
As a member of the Dukes over two seasons, Johnson logged 104 tackles, forced two fumbles and had two interceptions.
Johnson earned the nickname "Juice" for his prowess as a running back in high school, where his coaches believe he resembled O.J. Simpson.
"When I texted with him on Wednesday, it was all good. You wouldn't have known anything," Justin Wentworth, a former high school coach Johnson remained in contact with, told the Star Banner.
"He said everything was going good—typical upbeat, 'Juice' stuff. Getting this news hurts deep. It's a knife to the heart," Wentworth said.
- Will Green