During the attack, the gunman engaged in a firefight with casino employees, police said.
ISIS had claimed responsibility for the attack late Friday but officials have denied the attack was a terror-related incident and they repeated that denial Sunday. Carlos shot his automatic rifle into the air, but did not shot anyone in the casino.
Nearly all of the 37 people killed in the incident died from smoke inhalation as a result of the fire.
Carlos, who was sacked from job at the Finance Ministry for not disclosing required financial information, owed more than $80,000 and was forced to sell his vehicle, Albayalde said.
He questioned what he was going to do with the £1.5 million haul of poker chips he had tried to take away.
"He is heavily indebted due to being hooked on casino gambling, according to his immediate family", Albayalde told a media briefing on Sunday, reiterating the attack was not "an act of terrorism".
Police said the government-owned Philippine Amusement and Gaming Corporation banned Mr. Carlos from casinos in April at the request of Mr. Carlos's family. He was forced to sell his Ford Ranger pickup truck to help pay for his debts.
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The 43-year-old Carlos, a former DOF tax specialist, was ordered dismissed from the service by the Office of the Ombudsman on October 25, 2012 for "grave misconduct and gross neglect of duty" for failure to declare his house and lot in Tondo, Manila in his statements of assets, liabilities and net worth (SALNs) from 2003 up to 2006.
Duterte on Saturday night visited the wake of some of the victims at the Veronica Memorial Chapel and the Rizal Funeral Homes in Pasay City, and the Heritage Park in Taguig City where the wake of Elizabeth Panlilio Gonzales, wife of Pampanga Rep. Aurelio "Dong" Gonzales Jr., is being held.
He was later found dead on the fifth floor of a hotel connected to the complex, the 38th fatality of the night. When he got out of the elevator, Carlos sidestepped around a body scanner and made his way into the casino.
Resorts World Manila Senior Vice President Gina Alvarez added they have certificates of compliance in all the safety and fire requirements under the law. He said he didn't know where his son got the M4 assault rifle used in the attack. There are reports floating around that most of the security personnel fled themselves when they saw an armed intruder as they were not armed. The attacker didn't fire at fleeing casino patrons and employees but instead he set casinos tables on fire with gasoline, Albayalde told reporters.
The security footage showed Carlos casually exiting a taxi just after midnight and walking calmly inside the entertainment complex.
In the footage's last scenes, the gunman is seen exchanging fire with one of the hotel's security officers at a stairwell doorway.
The footage shows the attacker entering an elevator with two women behind him, shortly after arrival.