MANILA - The lone gunman who attacked Resorts World Manila last Friday started his gambling habit in cockfighting, an official of the Philippine Amusement and Gaming Corporation (PAGCOR) said.

PAGCOR chair Andrea Domingo said Jessie Javier Carlos started gambling in the cockpits of Pasay City, and ended up heavily indebted.

"Nagsimula siya actually sa sabong. Kilala siya sa mga sabungan sa Pasay City na Gurka. Doon din nagkautang utang siya at nagtalbugan ang mga cheke niya noong 2015, 'yun ay pagkatapos na naalis siya sa trabaho niya," she told DZMM.

(He started in cockfighting. He is known in the cockpits in Pasay City as Gurka. Because of this, he incurred a lot of debt and the checks he issued bounced. This was in 2015, after he lost his job.)

Domingo said that Carlos eventually tried his luck at casinos in a bid to raise enough money so he could bet in cockfights.

"Hindi na makapagraise ng itataya sa sabong, tinry niya ang pagka-casino," she said.

(He could not raise enough money for cockfights so he tried his luck at casinos.)

It was also Carlos' wife who asked PAGCOR to ban him from casinos.

PAGCOR earlier said it will conduct a separate investigation into the possible lapses in Resorts World Manila's response to the attack.

Thirty-seven employees and guests of Resorts World Manila were killed Friday when Carlos fired shots inside the casino and burned down gambling tables.

Carlos also died when he set himself ablaze in a room in the adjoining Maxims Hotel, which is part of the complex, before shooting himself, police said.