She approached the family and asked if their order was okay as the child had not received anything; the father replied everything was fine, and that the boy would eat at home later that evening.
This was when she noticed a big scratch between his eyebrows, as well as bruising on the side of his eye and arms, and she knew something was wrong.
"I started observing them and I could see that he was super quiet and sad," she said.
With the boy sitting opposite his parents, he could see her but they could not. So the quick-thinking employee wrote a sign asking if he was okay. He nodded "yes".
"But he didn't convince me," she said.
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Minutes later she wrote a second note asking: "Do you need help?" This time he nodded "yes."
She immediately went to the back of the restaurant and called 9-1-1. Orlando PD released a recording of the call, as Carvalho reported her worries.
"I'm super concerned and I don't know what to do, can you give me some advice? What I can do?" she can be heard telling dispatchers. "The boy is with bruises and he's not eating... the others are eating."
Police arrived within minutes and interviewed the parents. When officers rolled up the boy's sleeves they said he winced in pain; they found bruises all over his body, WFTV reported.
The boy's stepfather, identified as 34-year-old Timothy Wilson II, was arrested on one count of third-degree child abuse.
But when the boy was taken to hospital and examined, the full scale of the abuse was revealed.
He told detectives his stepfather hit him with his fists, a wooden broom and a back scratcher. he said he had been hung upside down from a door frame by his ankles, and strapped to a furniture dolly.
He said he regularly was denied food as punishment. Doctors found him to be 20lbs underweight. Even on the call to dispatchers, Carvalho assumed he was just 8-years-old.
Wilson was then re-arrested on three counts of aggravated child abuse, and one count of child neglect, while the mother was arrested on two counts of neglect for her failure to protect her son.
The boy was taken into protective custody, as was his four-year-old sister, who had been with them at the restaurant at the time.
"To be honest what this child had gone through was torture," Detective Erin Lawler said at the news conference. "There was no justification for it in any realm of the world. I'm a mother and seeing what that 11-year-old had to go through, it shocks your soul."
Orlando Police Chief Orlando Rolon added: "This could have been a homicide situation if she had not have intervened."
A GoFundMe set up to reward the heroic waitress has already passed $4,500.