Robert Ethan Saylor, 26, didn't understand why he couldn't watch the movie a second time and cursed security guards when they told him to buy another ticket or leave, the Washington Post reported Wednesday.
The guards were off-duty Frederick County sheriff's deputies who were employed part-time at the theater.
After cuffing Saylor and escorting him outside, the young man ended up on the ground showing signs of medical distress, said sheriff's spokeswoman Jennifer Bailey.
Saylor was pronounced dead short time later at a hospital.
The chief medical examiner in Baltimore determined he died of asphyxia and ruled the death a homicide.
"Ethan was developmentally disabled, not a criminal," said attorney Joseph Espo who is representing Saylor's parents.
He said the family believes the incident was handled the wrong way from beginning to end.