Investigators say the 10-month-old and 3-year-old were in a vehicle at the family's home on the 25000 block of Middleton Road and were temporarily left unattended.
Police say the toddler found a loaded handgun in the vehicle and accidentally fired the weapon. The single round hit the 10-month-old in the cheek. Family members say the infant will likely need facial scar treatment and minor reconstructive surgery, but is expected to make a full recovery.
The father, who owns a concealed weapons permit, told investigators that he and his wife were heading to an event at Expo Idaho and that he left his handgun in the family car to avoid carrying it inside the building.
The father said he forgot to take the handgun out of the car when they got home that night and forgot again the next day when they took the family truck to church.
"The charge of felony injury to a child would have been nearly impossible to prove in this case based on Idaho Statute, which requires proof that the action of the defendant(s) was willful and intentional," said prosecutor Bryan Taylor.
"The father in this instance made the mistake of leaving a loaded handgun in the car. It was a costly mistake, and nearly a deadly one, but it was not something he did willfully or intentionally. Had the child died, and thankfully he didn't, a charge of involuntary manslaughter would have probably been pursued."