MANILA - Former President Benigno Aquino III said he will be monitoring the investigation into the killing of Albuera town Mayor Rolando Espinosa inside a jail cell in Leyte.

Speaking to reporters at the sidelines of the Pray for 8 prayer-concert on Sunday, Aquino said he will be waiting for the results of the investigation.

"Tulad ng marami, siguro inaabangan ko 'yung mga imbestigasyon, tulad nung pahayag ni Senator (Panfilo) Lacson na buksan muli 'yung mga extrajudicial killings tapos inaasahan natin na mabilis 'yung pagsisiyasat dito sa pangyayaring ito at malaman natin anong nangyari dito," he said.

Albuera town Mayor Rolando Espinosa was shot dead inside his jail cell at the Baybay City Provincial Jail Saturday.

Albuera PNP chief Jovie Espenido said the former mayor was killed while being served a search warrant by the Philippine National Police (PNP) Criminal Investigation and Detection Group (CIDG) Region 8.

PNP CIDG Region 8 Supt. Melvin Marcos said Espinosa and fellow slain inmate Raul Yap fired shots while being served a search warrant.

Meanwhile, Interior and Local Government Secretary Ismael Sueno questioned the pre-dawn search of Espinosa's jail cell.

In a DZMM interview, Sueno said it is important to find out why a search warrant was issued for Espinosa who was already in jail.

The mayor turned himself in to the national police chief in August after President Rodrigo Duterte asked him and his son, Kerwin, to surrender over their involvement in the drug trade.