While local Philippine officials continue to investigate the attack that killed at least 36, newly released video indicates that the gunman may have acted alone, according to police.
The filing of criminal cases against the hotel-casino operator depends on the relatives of the victims, he said.
National Capital Region Police Office chief Director Oscar Albayalde led the news conference.
"He was heavily indebted due to being hooked to casino gambling, according to his immediate family", a police officer said.
Just last April 3, Carlos, who was said to be a regular at other casinos but not at Resorts World, was barred from entering all casinos by the Philippine Amusement and Gaming Corporation (Pagcor) upon request of next-of-kin, Albayalde said.
He was also heavily indebted and had even sold his Ford Ranger to pay off debts.
The finance department said Sunday that Carlos was sacked as a tax specialist in 2014 for not declaring properties and for taking mysterious loans far more than a bank would lend.
The Islamic State claimed responsibility for the attack, with a report on its self-styled Amaq news agency saying its "fighters" carried out the attack, but Philippine authorities continued to insist on Saturday that a mentally disturbed man had been attempting a freakish solo robbery. Based upon reports such as these, the assumption was made by authorities that it could potentially be a planned terrorist attack.
"If he is really a terrorist, he could have shot everybody there", said Albayalde, commenting on the security footage.
The police chief confirmed that the attack was not an act of terrorism, adding that it was a robbery attempt. He had on a black jacket when he was dropped off at the casino on Friday at 12:07 a.m.by a taxi.
The video also showed him breaking into a secure room where chips and money were being kept, apparently intent on stealing what he could. Carlos then took out an M4 assault rifle from his bag.
He barged into the casino, set ablaze gaming tables, slot machines and a dining area.
Unfortunately, while the motive of the gunman was to rob the casino, there were many Resorts World Manila victims because of the fire. He stuffed chips totaling 113 million pesos ($2.3 million) in a backpack, which police later recovered, he said.
A security guard tried but failed to stop Carlos as he was brandishing a baby armalite. Later footage shows him with blood on his face. Inside the room, and out of view of security cameras, he lay down on the bed, set himself on fire and fatally shot himself, Mr. Gomez said.
The lone gunman who carried a deadly attack at a Manila casino was a troubled man who was in debt and had a gambling problem, police say.