Police said Roopa Santhan, who arrived at Arichalmunai area from Ambarai in Sri Lanka along with four others on December 14, had kept in constant touch with the trio through their cellphones.
Police suspect the three persons might have helped the others escape after their arrival.
Santhan was nabbed by police with the help of the Coast Guard a short while after his arrival. He was arrested for violating the Passport Act.
A local court had yesterday remanded him to custody till December 30 and ordered that he be lodged in Puzhal Prison near Chennai.
He also said he was not sure of the whereabouts of those who had come with him.