WAIANAE, Hawaii -- The dog that killed a 2-month-old baby and attacked the child's mother was euthanized on Monday.

The attack happened just after midnight on Sunday morning at a home on Kakaiapola Street in Waianae.

The Hawaiian Humane Society said the family stepped forward and asked for the animal to be euthanized.

The Medical Examiner's Office on Monday said the baby, Iokepa Liptak, died from head injuries.

The mother, identified as Blossom, returned home on Monday limping from a leg injury.

Distraught family members did not want to speak on camera as loved ones gathered for a prayer session for Liptak.

The Hawaiian Humane Society held the dog known as Penelope Rose in isolation at its headquarters until it was put down.

Investigators were not able to determine the dog's owner.

"There was no one there that he could talk to as far as ownership of the dog," said Kawehi Yim, of the Hawaiian Humane Society. "He took the dog and brought it to Humane Society and we've had it in custody ever since."

Officials said it is unclear why the dog attacked the baby. Neighbors described it as aggressive, but field investigators said the animal was not aggressive when it was removed from the home.

"There were nor significant challenges or behavior challenges with it. Our officers were able to retrieve the dog and bring it back to the Humane Society and put it into the kennel," Yim said.

Child Protective Services officials said they are doing a routine investigation to see if there was possible neglect or lack of supervision.