The tiny body of a newborn baby boy was found in a plastic bag inside a sanitary pad bin in a women's toilet at Tampines MRT station in June.
Yesterday, State Coroner Marvin Bay recorded an open verdict at an inquest into the infant's death.
A 75-year-old cleaner had found the baby, with his umbilical cord and placenta still intact, while she was emptying the bin at about 1.20pm on June 3. A paramedic later pronounced the infant dead.
There were no visible injuries on the baby, nor any signs of decomposition, or of the infant having been born inside the toilet.
The baby's mother is believed to have come from Batam and returned there, the inquiry heard.
Closed-circuit television footage showed a woman entering the toilet at about 10am that day and leaving at about 11.10am. She had difficulty walking.
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Police investigations showed she was probably a 35-year-old Indonesian, referred to as Ms M, who came to Singapore, visibly pregnant, on May 25 through the HarbourFront Ferry Terminal. She was with two compatriots, aged 26 and 31.
They were also seen entering the toilet several hours before she did, on June 3. One was carrying a bag which seemed heavy. They left 20 minutes later with the bag, visibly lighter and swaying about.
All three women have left the country. They are believed to have been helping out at a Hari Raya Bazaar on the open field in front of Tampines MRT station. All their names were redacted from court documents.
In an autopsy report on the infant, a forensic pathologist wrote that the cause of death of the full-term infant could not be determined and stillbirth could not be ruled out.
Based solely on autopsy findings, it was not clear if he had been born alive. Intentional suffocation could not be ruled out as it might not leave any injuries on a newborn.
But the baby might also have suffocated via natural processes, if he did not receive enough oxygen just before, during, or just after birth.
He could also have died from causes such as dehydration, or low blood sugar level if he had not been fed after birth.
Said Mr Bay: "The documentary and circumstantial evidence strongly point to the three women being connected with the discovery of the male infant, with Ms M likely being the mother.
"Ms M's absence from jurisdiction has made it impossible to confirm her maternity, as the DNA samples collected require a reference sample from her. It is understood that the three women, who have left Singapore, remain as persons of interest.
"Notwithstanding this, the fact that the forensic pathologist has not been able to ascertain the cause of the infant's death, or even exclude the possibility that the infant was not born alive (i.e. stillborn), would necessarily constrain me to deliver an open verdict for this case," the coroner added.