They said he was a Filipino, Jessie Javier Carlos, who had heavy gambling debts, and was not a terrorist.
Manila's police chief Oscar Albayalde told reporters that the attack was believed to have been carried out by only one person.
Carlos was found dead several hours after the attack.
"He is heavily indebted due to being hooked on casino gambling, according to his immediate family," said Mr Albayalde.
Carlos had entered the capital's Resorts World Casino and began shooting, before setting fire to a gaming room.
He also filled a backpack with gambling chips worth 113m Philippine pesos (£1.7m, $2.3m).
He later fled to the hotel section of the complex, leaving behind the backpack and entering a hotel room.
He died after setting himself on fire, said police.
"He lay down on the bed, covered himself with a thick blanket, apparently poured petrol on the blanket and burned himself," national police chief Ronald Dela Rosa said on Friday.
Previously, he was said to have poured petrol over furniture and rugs, causing them to catch fire immediately.
Although the casino fire was not large, thick smoke caused the multiple deaths.
Police in the Philippines say they have identified an attacker who killed at least 36 people when he set fire to a casino in Manila on Friday.