"He's facing two counts of first-degree assault, two counts of first-degree child abuse, so very substantial charges for him as a 17-year-old," said Frederick County State's Attorney Charlie Smith.
Barnes also faces two counts of second-degree child abuse.
Officials said the infant's mother went to Frederick Memorial Hospital for a one-month well visit when hospital staff noticed injuries in line with abuse. It is unclear if the mother was aware of the abuse but court documents show the injuries occurred two to three weeks before the baby's hospital appointment.
"We know that the abuse occurred prior to the time they took the child for a one-month well business," said Smith.
Court documents show that Barnes expressed to police that he felt "stress" prior to the incident and that he took out his "frustration" on the crying baby.
Due to the severity of the abuse, Barnes will be charged as an adult regardless of his age, officials say.
"Ultimately the judge will have to decide whether he's going to need to be tried as an adult or not. In other words, he can try to have this case sent back to the juvenile system but we will fight that," said Smith.
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