A toddler who was critically wounded on Monday in an attack that also left her mother dead underwent brain surgery in Bangkok last night after being flown from Phnom Penh in the early hours of yesterday morning.

After having an initial operation to reduce the swelling around her brain shortly after her arrival at Bangkok General Hospital at about 4am, 19-month-old Dana Oele was placed in intensive care, according to a source at the hospital who asked not to be named because he was not permitted to talk to the media.

“The operation this morning went well. They tried to stop the bleeding. They tried to stabilise her during the day, tried to reduce the swelling around her brain using various methods,” the source said.

“This afternoon we were told that hadn’t worked. And [doctors] found not much brain activity. This evening, she has gone for brain surgery, and we should know in the next three or four hours,” they added. “The situation remains critical.”

Her father, Joris Oele, 34, is staying at Bangkok General in a room provided by the hospital, according to a hospital spokeswoman.

“Dana went to the intensive care unit for treatment last night. There is still swelling around the brain, so there are still risks,” she said.

Police at the scene of the attack on Monday said Dana had been stabbed, but after being examined in Bangkok, the health official said, it was discovered that a blow to the head with a blunt object had caused the trauma.

“The brain swelling was caused by blunt trauma, not a stab wound,” she said.

Two other wounds found on Dana’s body were not serious, the spokeswoman added.

Dana’s mother, Daphna Beerdsen, 31, was found dead in the family’s rented house in Phnom Penh’s Chamkarmon district off Norodom Boulevard at about 9am on Monday morning.

Beerdsen had been stabbed six times in an apparent struggle with the attacker. Police have yet to name any suspects in the case.

Mom Sitha, Phnom Penh municipal foreign police chief, said yesterday that police had questioned five witnesses, however had not yet identified any suspects.

“We do not yet have a suspect, because police have not had a final meeting to conclude [the investigation],” he said.

He added that the police forensic team had found no evidence that Beerdsen had been raped. Police investigators on Monday took samples for testing to determine whether a sexual assault had taken place.

Run Chantha, the local village chief, said that two British Embassy security guards had been posted at the gate of the house. The embassy provides consular assistance to Dutch nationals in Cambodia.

“The house is locked and two security guards were posted at the home’s gate around the clock,” Chantha said.

He added that security would be stepped up in the neighbourhood following the murder.

“This is the first murder to happen in my village, and we are tightening the security in the area now,” he said.