The Federal Police Department said in a brief statement posted on its website that the man turned himself yesterday night in the central-western state of Mato Grosso. No further details were provided.
Justice Minister Alexandre de Moraes on Thursday announced the arrest of 10 Brazilians who police said had pledged allegiance to the Islamic State and discussed on social media the possibility of staging attacks during next month's Games.
The man arrested yesterday is one of two additional suspects that Moraes said were being sought.
Investigators said none of the suspects was of Arab descent. They ranged in age from 20-40, except for one minor.
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The top military aide for Brazil's interim government said last week that concerns over terrorism had "reached a higher level" this month after a truck attack that killed scores of people in Nice, France.
Officials did not raise the country's terror alert level Thursday following the raids in Brazil.