The two-year-old boy then lay back down again and doctors confirmed that he was indeed dead.
"Dead people don't just wake up and talk. I'm determined to find out the truth," said Antonio Santos.
His son Kelvin Santos was in the coffin just an hour before the funeral when startled mourners said he'd come back to life.
He apparently smiled, looked round, drank his water then reclined back in his coffin.
His dad couldn't wake Kelvin again and carried him to hospital in Belem, northern Brazil.
But doctors were mystified as to what happened but confirmed he was dead.
"During the wake I held Kelvin and said, 'Son, come back to daddy'," said Antonio.
"And a few hours later my son sat up in the coffin and said, 'Daddy, give me water'.
"Everybody started to scream. We thought a miracle had taken place and our boy had come back to life.
"Then he lay down again and didn't move again. We couldn't wake him."
Kelvin died from pneumonia and respiratory failure in Aberlardo Santos Hospital at 7pm on Friday following a five-day fever.
What a bizarre tale, if true. What do you think?