She died of a prescription drug overdose at a nursing home.
But how exactly?
If she had been overdosed, there would have been a shortfall in the balance of the drug. But a check revealed that there was no shortfall.
However, State Coroner Imran Abdul Hamid said yesterday that record-keeping at the home was "below par".
He also said that the evidence given by the nursing home officers did not tally with the records. Coroner Imran said he accepts that the cause of death was an overdose but he could not conclude how the overdose occurred.
Madam Tan Suat Cheng, 78, a resident at the Simei branch of Orange Valley Nursing Home, was prescribed fluoxetine, an anti-depressant better known as Prozac.
She was prescribed 20mg of the drug on Tuesdays, Thursdays and Saturdays, and 40mg on Mondays, Wednesdays, Fridays and Sundays.
An inquest into Madam Tan's death revealed that she had been taking these alternating doses for over a year before she died on April 12, 2009.
But should she have been given that amount to begin with?
Two expert witnesses gave conflicting accounts on what dosage Madam Tan should have been given.
Dr George Paul, a senior consultant forensic pathologist at the Health Sciences Authority said there was documented evidence of overdosing.
He said she was given way above the suggested dosage in relation to her body weight.
The court heard Madam Tan, whose post-mortem weight was about 36kg, was "grossly underweight."
Dr Paul also noted that she was suffering from "so many illnesses concurrently in her," including hypertension and left-sided stroke.
He said the usual dose of fluoxetine is anywhere from 5mg to 20mg a day as maintenance or 60mg once a week for a normal-sized person who weighs about 65kg to 70 kg and does not have any of Madam Tan's other illnesses.
But Dr Francis Ngui, a senior consultant psychiatrist, doubted that the prescribed dosage contributed to Madam Tan's death.
He said that even though doses differ from patient to patient, they are expected to be in the range of 20mg to 60mg per day.
Dr Ngui, who was appointed by the Academy of Medicine as an independent expert, added that based on available literature, fluoxetine is a safe drug, even in acute overdose involving much higher doses ingested.
The court heard that Madam Tan was supposed to be given the drug once a day every morning.
Prescribed medication at the home was recorded on a chart and nurses there would then dispense the drugs.
Based on the records, it appeared that a nurse at the home gave Madam Tan the drug once around 8am and then again at 6pm on April 9, 2009, a Thursday.
The nurse, Ms Maria Victoria Acijalado Calub, explained that this was because she had signed in a wrong column on the medication chart.
She also said she did not give Madam Tan the drug that evening.
Signed wrongly, too Ms Calub was not the only one to say she made a mistake that looked like a double dosage.
The next day, another nurse, Ms Diadema Onatec Pacheco, said that she had inked her initials in the wrong columns on the medication chart.
So it looked as though she had given Madam Tan an overdose, even though she had not.
Responding to queries from The New Paper, a spokesman for Orange Valley Nursing Home admitted there were "clerical errors in documentation".
She said: "Medication records at the home were in place and in accordance to best practices.
"Ms Calub and Ms Pacheco had also acknowledged they had signed in the wrong columns after serving the medication."
The spokesman added: "None of the staff members left their jobs because of the incident. However, MsPacheco has since gone home after her employment contract expired."
A spokesman for the Ministry of Health (MOH) said that it takes a serious view of the matter.
He said: "We have just received the coroner's report and will study the report carefully. We are in touch with Orange Valley Nursing Home on the matter and will provide an update as soon as we are able to share our findings."
When TNP visited Madam Tan's 43-year-old son's flat in Chai Chee yesterday afternoon, a man who came to the front window declined to comment.