The accused, currently residing at a flat on Marine Drive, was arrested on the basis of a complaint by a woman from Thrissur.
The trio asked the girl to meet them at Kundara in Kollam and abducted her in a car before raping her.
His Mexican club Pumas UNAM announced they had terminated his contract with immediate effect.
The world championship medallist said she received death threats.
Unnikrishnan is a member of Mavoor Panchayat.
The Brazilian defender denies any wrongdoing.
Sunu is the third accused in the case pertaining to the gang rape of a woman in Thrikkakara in Ernakulam.
Nasu, a native of Lakshamveedu colony in Anchal, was taken into custody after the decomposed and naked body of a woman was found in a deserted railway building at Chemmamukku in Kollam.
A native of Perambra, the differently-abled woman was taken to Malappuram and Kozhikode districts and abused sexually, as per her complaint.
The cops also nabbed the bakery owner Baburaj, aka Kannan (51), and booked him under the Protection of Children from Sexual Offences Act.