Singh interrogated them at the Sooramangalam Women Police Station after they were brought there from the prison with tight police security, they said.
Later, advocate Jakir Ahamed counsel of the duo alleged that Fakruddin and Malik had complained to him that medical check ups were not provided to them.
He said his clients complained of severe tooth pain.
The duo were arrested in connection with the July 19 murder of BJP state general secretary V Ramesh.
Panna Ismail and Bilal Malik were nabbed at Putur on the Tamil Nadu-Andhra Pradesh border on October 5 in a joint operation by police forces of both states.