The four-month-old baby was in a stroller when his 21-month-old cousin pushed it, causing it to fold and fall to the ground.
After the fall, the baby did not cry and appeared to be fine. But he was found to be unresponsive the next morning.
A frantic effort by his aunt and paramedics to save him was unsuccessful. He was later pronounced dead.
In a coroner's inquiry into his death yesterday, the court heard that he had been under the care of his aunt, 29, the mother of the 21-month-old, when the tragedy occurred. She is the half-sister of the baby's 33-year-old mother.
The deceased cannot be named to protect his young cousin's identity.
On March 2 last year, his aunt, Ms Linda, and her fiance, Mr Zul (not their real names), 22, decided to get tattoos.
The jobless couple took both children in separate strollers to Nee Soon Tattoo Shop at around 3pm that day. They took turns looking after the children as the other got inked.
Investigation officer Staff Sergeant Eugene Chua told State Coroner Janet Wang that the couple took a taxi back to the baby's mother's flat at about 8pm.
At around 10pm, Ms Linda wanted to make a sandwich and the couple decided to head to a nearby supermarket with the two children.
The baby was placed in his stroller on the corridor and Mr Zul went back into the flat to get the toddler's stroller.
It was then that the toddler pushed the stroller, causing it to fold up and topple to the ground with the baby inside.
Staff Sgt Chua said: "According to (the baby's aunt), the stroller folded up because it was not fully unfolded and the safety lock was not properly secured.
"(She) immediately carried (the baby) out from the stroller. (She) observed that (he) was not crying and appeared to be fine."
She could not tell if the baby had hit his head against the frame of the stroller or the floor when it collapsed.
After that, she unfolded the stroller completely until she heard a click, which meant that the safety catch was locked.
All four then went to the supermarket and returned at about 11pm, after which Ms Linda put the children to sleep.
She and Mr Zul fell asleep at about 1am.
At around 6am the next day, Ms Linda heard her nephew crying and got up to make some milk.
But he did not want to drink it and he fell asleep after she gave him a pacifier.
Three hours later, when she wanted to change his diaper, she saw him lying face down. When she turned him over, she realised that his fingers were stiff and brownish liquid was leaking from his nose.
When he was unresponsive, she woke Mr Zul up and called for an ambulance.
The Singapore Civil Defence Force received the call at around 9.50am and call operator Roslina Zumahar, 22, instructed Ms Linda to perform cardiopulmonary resuscitation (CPR) on the baby.
She used three fingers on each hand to press down on the baby's chest region twice while Mr Zul blew into his mouth.
"While performing CPR, (she) observed brownish fluid coming out from (the baby's) mouth and nose.
"(They) then stopped performing CPR on (him) as they were afraid that they would injure him. They proceeded to wait for the ambulance to arrive," said Staff Sgt Chua.
An ambulance arrived at 9.59am and paramedics Gina Lim Hui Min, 22, and Maryanah Rahmat, 26, reached the flat about five minutes later.
They placed a "heart start machine" on the baby to try and resuscitate him. Ms Maryanah also carried out CPR while Ms Lim tried to insert an oral airway into his mouth, but to no avail.
He was taken to the National University Hospital, where attempts to resuscitate him were also unsuccessful. He was pronounced dead at 10.56am.
An autopsy report dated March 4 last year said the baby had suffered injuries including fractures on his skull and left rib. (See report above.)
In an e-mail dated Feb 13, senior consultant forensic pathologist from the Health Sciences Authority, Dr George Paul, told Staff Sgt Chua that the baby died from head injuries.
Coroner Wang will deliver her findings tomorrow.
WHAT COULD HAVE CAUSED THE SKULL FRACTURES
It is likely that the skull fractures found on the four-month-old baby were caused by the impact of his head hitting the ground or the frame of the stroller, a police officer told a coroner's inquiry into the child's death yesterday.
Investigation officer Staff Sergeant Eugene Chua said: "The folding and collapse of the baby stroller was a result of (it) not being properly locked and secured when (the baby's aunt's) own 21-month-old son pushed on it."
The aunt, 29, and her fiance, 22, who were both jobless, did not give the baby immediate medical attention as he did not show that he was in pain after the stroller fell on the floor.
"Based on the evidence uncovered in the course of police investigations, (officers) do not suspect any foul play in the death of (the baby)," said Staff Sgt Chua.
This article was first published on February 17, 2015.
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