Davao City (CNN Philippines) — The Davao City Police filed on Wednesday multiple murder and multiple frustrated murder complaints against nine suspects said to be involved in the Davao City bombing last September 2.

Authorities identified one primary suspect, and are temporarily withholding the release of his identity. Charges were also filed against the other, still unknown, attackers — five men and three women.

Investigators said the primary suspect left the bag containing the bomb in a massage parlor along Roxas Avenue night market. Witnesses said he wore a mask and a bonnet the whole time, even while he was having a massage. The blast killed 15 people and injured dozens of others.

The police are also checking if the main suspect is linked to terrorist groups or other personalities with motives for the attack.

The police earlier released a composite sketch of the principal suspect — a man about 30 years old, 5' 7" to 5' 8" in height, with a slim build and fair to dark skin.

Look: Sketch of Davao City bombing suspect

A ₱3 million bounty has been raised by the Davao City government for information leading to the arrest of suspects.

Asked about the involvement of Talitay, Maguindanao Vice Mayor Abdul Wahab Sabal in the bloody incident, Dubria said he could not confirm or deny this since the investigation is being handled by higher command.

Watch: The deadly Davao City blast in 90 seconds

Following his arrest last week at the Cotabato airport, Sabal went through inquest at the justice department Saturday afternoon for suspected illegal drug activities and involvement in the Davao blast. Sabal is on the list of alleged "narco-politicians" released by President Rodrigo Duterte.