The Cuddalore district police on Sunday formed three special teams to probe the blast in a house in Chidambaram on Saturday.
History-sheeter Mohan Ram, who was critically injured when a country-bomb exploded, is undergoing treatment at JIPMER Hospital here. The police are keeping a strict vigil on him.
A special team nabbed one of the four suspects who had given the police the slip.
Arul, an employee of Annamalai University who had escaped from the hospital on Saturday, was picked up in the city from the house of one of his relatives.
A special investigation team has been sent to Dindigul to collate information on Mohan Ram.
A low-intensity country-bomb went off in a house in a residential locality, which was rented by Arul, injuring five persons.
Police suspect Mohan Ram to be the key accused in the case of manufacture of country-bombs.
Arul, who was injured in the eyes, was being interrogated, police sources said.