Coleman, Mallory and Franklin joined in, punching, kicking and stomping the 124-pound Tillman, authorities said.
Daniel said Tillman's slight stature had nothing to do with the severity of his injuries. The number of attackers wasn't a factor either.
"One guy could've done the same thing," Daniel said.
The injury is similar to a patient suffering a punctured lung from broken ribs, Daniel said, except that this one was fatal.
"It would take just a few minutes [for Tillman to die] because of the loss of blood," Daniel said.