“We’ve got 30 detectives working for me. They’re devastated that they missed this person by 12 hours,” he told reporters on Monday.

“I was in the investigation centre when we put a name to the face and it was a very happy room, only for us to do a check in 15 minutes and find out we’ve lost him.

“I was deflated, but that deflation quickly turns into determination and resilience to get the job done.”

Dalton said the man was “aware of police methodologies” and had been conducting “counter-surveillance activities”.

Police believe the man drove to Sydney a day after the incident before departing Australia on August 31.

The 33-year-old had no family or criminal record in Australia and had worked in Queensland, NSW and Victoria.

The man had either been on a working visa or a holiday visa since first coming to Australia in 2019, Det Dalton said.

Police have called on interstate and international partners to help track down the man.

CCTV and enhanced images of the man were released since the incident, which left the baby with significant burns to his face, arms and legs.

The infant has undergone multiple surgeries since the “cowardly” incident at Hanlon Park, Stones Corner.

“We can find no motive,” Dalton said.

“I’ve seen a lot of disgusting acts … but [this] probably was of the most disgusting ones I’ve come across.”

The family said the little boy had been incredibly resilient despite the “traumatic and difficult” time.

“He’s up and about, walking and causing chaos,” his mother said.

Police previously described the incident as deliberate and unprovoked.

“It is callous and cowardly,” Dalton said.

A GoFundMe page for the infant has so far raised more than A$150,000 ($243,000).