MANILA — The two suspects in a deadly bomb attack during a Catholic mass at the Mindanao State University (MSU) last weekend are both members of the Daulah Islamiyah-Maute Group, the Philippine National Police said on Wednesday.

The PNP identified the suspects as Kadapi Mimbesa also known as "Engineer", and Arsani Membisa alias "Lapitos.

Engineer is believed to be an improvised explosive device (IED) expert who has existing warrants of arrest for cases of kidnapping, serious illegal detention, and illegal possession of explosive device.

A victim identified Engineer, who sat beside her inside MSU's gymnasium in Marawi during Sunday's attack.

"The suspect was seated on her right side of the chair, he acted so suspiciously and he was uneasy and he was on his phone calling somebody while the left of his arm was fixing something under the chair," Bangsamoro police chief PBGen. Allan Nobleza said.

The witness identified Engineer even when he was wearing a face mask because they had eye contact.

"Nakita niya yung mata, so nakilala n'ya sa mata itong tao, pati yung height. When the CIDG presented three photos to this witness, she cried after seeing the photo of this guy," Nobleza added.

Lapitos, on the other hand, was the driver of the motorcycle the suspects used.

Based on CCTV footage, the two suspects were seen riding a motorcycle to the MSU gymnasium.

Engineer was wearing a white long-sleeved shirt, gray pants, a cap and a face mask. He was seen carrying a black bag. Lapitos was wearing a black hoodie, red cap, denim pants and face mask.

At around 7:03 a.m., they were seen entering the gym. About 8 minutes later, Engineer left the gymnasium without the black bag, followed by Lapitos.

Engineer also talked to someone on a cellphone that authorities believe could have been used as the detonating device.

"Based on our investigation and findings, the cellphone was used as a command or remote control in destroying the bomb," Nobleza said.

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According to PNP, two explosives were used in the bombing: a 6-mm mortar and a rocket propelled grenade.

Authorities are still looking at retaliation as a motive behind the bombing.

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Military chief General Romeo Brawner earlier said the bombing might have been a revenge attack for government operations against three Islamist militant groups -- Dawlah Islamiyah-Philippines, Abu Sayyaf and Maute -- in western Mindanao in recent days.

Pro-Islamic State Maute and Abu Sayyaf militants -- including foreign and local fighters -- held Marawi under siege in 2017.

The Philippine military wrested back the ruined city after a five-month battle that claimed more than 1,000 lives.

— With a report from Agence France-Presse

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