Teodora Carlos, the mother of the gunman, identified by police as 42-year-old Philippines national Jessie Carlos, said that he was a "good person" who changed when he started frequenting casinos.
"My son was just a victim... he fell victim to the casinos," she said, according to a translation provided by CNN Philippines.
She said that the family was struggling to come to terms with what Carlos had done.
"I still don't want to accept that it was my son, because my son was a good person."
Gambling addict banned from casinos
He had been banned from all casinos by the Philippine Amusement and Gaming Corporation at the request of his family, which police are looking at as a motive for his attack at the Resort World Manila casino in the early hours of Friday.
"He knew that he couldn't just go into a casino to gamble because his picture would be posted there and he wouldn't be allowed inside."
Suspect former government official
The suspect was a former tax specialist at the Department of Finance, Albayalde said. He was fired in 2014 due to false declarations and nondisclosure of assets and had racked up bank debts of 4 million pesos ($81,000).
Albayalde said the incident is now a "closed case" with regards to the identity of the perpetrator.
Shots fired, gaming tables burned
Carlos entered the Resorts World Manila shortly after midnight Thursday, firing shots from an assault rifle and setting fire to gambling tables.
He ransacked a room and stole gaming chips totaling 113 million pesos ($2.3 million), Philippine National Police Chief Ronald Dela Rosa said. He stuffed the chips in a backpack, which police later recovered, he said.
During the attack, the gunman engaged in a firefight with casino employees, police said.
Carlos was shot and wounded by security guards, and retreated into a hotel room, where he doused a bed with gasoline and shot himself, police said.
CNN Philippines reported he was found in the room, his body burned beyond recognition. It was next to an automatic weapon and a .380-caliber pistol.
Carlos' mother urged others to look to her son's case as a reason to avoid gambling.
"I think what happened to my son shows everyone not to get into gambling so that their families will not be ruined."