According to a report by the Portuguese news agency Lusa, the public ministry in Beja, in the region north of the Algarve, will be looking into the circumstances surrounding the death of the boy who died on January 8.
The toddler was attacked late on Sunday afternoon at his home in Beja by a pitbull that lived in the house with the family.
News reports have said that the pitbull was nine years old and that it belonged to the uncle of the boy who also lived in the same house with the parents and grandparents of the toddler.
Pitbulls are considered to be a breed of dangerous dog in Portugal and there are strict guidelines about who can own the dogs and how they must be housed and walked on a lead with a muzzle.
Initially after the attack the mother of the child drove him to hospital in Beja but he was quickly transferred by helicopter to hospital in Lisbon as it had been assessed that he had sustained serious brain injuries from the attack.
Speaking on Monday evening the grandfather of the boy, Jacinto Janeiro told press that he was shocked by the attack because the dog had always been “very sweet” and had “always lived with children”.
He said that the dog was in the kitchen of the house at the time of the attack and that the small boy had gone into the dark room and then fallen over which provoked the attack.
He added that in the nine years that the dog had been living with the family that it had never before attacked anyone or harmed a person in anyway.
However, according to Lusa, various sources close to the family said that the grandfather himself had been attacked by the dog in the past on at least two occasions and he had required hospital treatment.
Following the death of the boy the dog was taken by municipal vets and is now being kept under observation but because of the nature of the violent attack it will be destroyed next week.
When the dog was taken to the vets there was no paperwork with it as required by law with the uncle of the boy claiming that he could not find them.
According to Lusa the dog is not registered with the local council as being a dangerous dog but it does have a chip as required by the law in Portugal.
An autopsy of the boy is due to take place today as is usual in a case such as this and an investigation is to be launched as to how the tragedy happened.