In a statement, Fariñas assailed the NBI for what he claimed was the "haphazard" filing of the case against him with the Department of Justice (DOJ).
Fariñas said it only bolstered his earlier suspicion that politics was behind the murder charges against him.
"Based on the charge sheet, the evidence against me is very weak and yet the NBI filed the case with the (DOJ). I am confident that the case against me will eventually be dismissed," he said.
Aside from Fariñas, the NBI charged nine other people with obstruction of justice in the killing of Vice Mayor Jimmy Chua.
They included Superintendent Joel Pagdilao, Laoag City police chief; SPO3 Arthur Mateo, chief investigator; and councilor Melvin de la Cuesta, the supposed witness against Fariñas.
De la Cuesta earlier alleged that a hired killer shot and killed Chua in front of the Eagle’s Nest Restaurant in Laoag City before dawn of Feb. 2.
He, however, later recanted his original affidavit and tagged Fariñas as the one who accidentally shot Chua in his and Pagdilao’s presence inside the restaurant.
Fariñas alleged that a powerful Ilocos politician had pressured De la Cuesta to make a retraction and tag him (Fariñas) as the one who killed Chua.
Meanwhile, the 66 officers and members of Laoag City’s Association of Barangay Chairmen, in a manifesto, threw their support behind Fariñas.
"We are aware of the controversy implicating Mayor Michael V. Fariñas and that we find this totally unbelievable because of the extensive period we have known and dealt with our beloved mayor," the manifesto stated.