It very explicitly guesses that she is black, based solely on statistical inference.
From TFA: "Statistics suggest that Maria was undoubtedly poor and, most likely, Black."
To read this as established fact is analogous to asserting as established fact that if you roll a six-sided die, you will certainly get a number <= 4. Probable, but not fact.
A careful read also reveals that none of the woman's actual identifying information was revealed, including her name, for her own privacy:
"We’ll call her Maria, the most common female name in Brazil, because authorities have not disclosed her real name in order to protect her identity."
Follow-up edit: thank you for your correction, I appreciate the epistemic humility and good-faith dialogue.
