Relatives of a 15-year-old boy charged with murdering his newborn son in Bunbury Hospital say the teenager is shattered and confused.
The family expressed concern about the teenager's welfare after he appeared in Perth Children's Court yesterday.
Prosecutor Sean Stocks said police had received autopsy material which had led to an initial charge of grievous bodily harm being substituted with the charge of murder.
The teenager, who appeared on a video link from Banksia Hill detention centre, indicated that he understood the charge before the case was adjourned for four weeks.
The baby was critically injured on February 15 and was taken off life support about a week later.
Outside court, one of the teenager's elder sisters said her brother was confused and stressed.
"I have been going out to visit him regularly at Banksia Hill," she said.
"I have been trying to talk to him about it. He is just confused, he is shattered. We all are. We had a chance to meet our nephew. He was a beautiful baby boy."