Ordered to submit their answer to the charge of double murder were Felix Robregado, Gerard Mendoza and Iner Bulusan.
Robregado is now under the custody of the Philippine National Police-National Capital Region Office following his surrender last week. The rest are still at large.
Aguinaldo and his bodyguard, Police Officer 2 Joey Garo, were shot dead on the night of June 12 in front of the congressman’s rented apartment on Magallanes street in Tuguegarao.
Aguinaldo was shot four times in the nape and left arm, and took another four bullets in the back. He died 30 minutes after being taken to St. Paul Hospital.
The NPA, military arm of the communist movement, owned up to the ambush, saying the former Philippine Constabulary officer owed "blood debts" to the people.
Robregado vehemently denied his involvement in the ambush-slay of the Cagayan congressman, saying the PNP owes him an explanation why he is being linked to the crime.
Despite the denials, police said they have a strong case against Robregado after a 59-year-old school teacher identified the suspect from police file photos of known NPA rebels. The witness said she was positive Robregado was among the eight men who waited for Aguinaldo and killed him.
The prosecutor’s office warned Robregado and other suspects to comply with the order, saying failure to do so "will be deemed as a waiver on their part and result in submission of the case for resolution based on evidence at hand."
Meanwhile, Central Luzon police director Chief Superintendent Enrique Galang denied reports that members of Philippine Military Academy (PMA) Class 1972 will be hunting down the killers of their slain classmate.
Galang said he was interpreted wrongly when he asked for everyone’s help in bringing justice to the slain congressman and his family.
It was earlier reported that the Class of 1972 had vowed to go after Aguinaldo’s killers, accusing the Communist Party of the Philippines, National Democratic Front, and New People’s Army as perpetrators of the crime.