The 15-year-old, found in a container, survived the six-day journey from Bangladesh's port city of Chittagong to Malaysia's Port Klang without a morsel of food and water.
All three victims suffered non-life-threatening injuries and are expected to survive, the Boston Police Department said.
The boy was with his mother when he turned himself in with two other teenagers and confessed to stabbing the victim.
Officials are looking at the possibility of treating the case as a justifiable homicide.
The brother of the deceased woman, who was expecting the child on April 12, said she was excited when she learned she was going to be a mother.
"The partially open chute prevented a complete freefall, but the landing was uncontrolled and at an accelerated pace," firefighters were quoted saying.
Two of the children, aged 1 and 5, were found inside another stolen vehicle. The infant was found at another location later.
Officials believe the woman was stabbed at another location before being driven to the area where her body was found.
The police arrested the suspects for sexually assaulting the unidentified victim and filming the abuse.
The Florida authorities could not locate the mother. "We will hold her accountable because she left this child abandoned in the woods, ostensibly, to die," the Polk County sheriff said.
The two young victims sustained head trauma and lacerations as a result of the vehicle collision that occurred when the female driver was shot.
"It's humiliating, it's embarrassing," the victim said referring to the gas station employee's behavior toward her.
"I'm not proud of what I was, but I am proud of who I am today," Richard McNally, who goes by the stage name Irish Bull, said.
The child was rescued last month from Dayton International Airport where the kidnapper left him.
The officer was forced to fire a shot at one of the dogs as it was being aggressive toward local residents.
The officers have since been fired.