A Singapore General Hospital (SGH) senior consultant threatened her 81-year-old doctor-father with a knife, held his neck in an armlock and even bit him on his arm.

Tham Kwang Wei, 43, who was diagnosed with mental illness after the incident last year, admitted threatening and causing hurt to her father, Dr Tham Ngiap Boo.

A Community Court heard yesterday that Tham had approached her father at his clinic in Whampoa Drive on Sept 30 last year.

She claimed that he owed God $150,000 and told him to give her the money so she could return it.

When he refused, she took out an 18cm-long knife and held it to his neck. She told him to give her a cheque for $150,000 or follow her to the bank to withdraw the money.

He tried to push her away and called for help. His clinic assistant opened the door but was forced out by Tham.

Tham forced her father onto a chair and held his neck in an armlock. He was struggling and trying to free himself when another staff member came and took away her knife. Tham then bit the victim's left forearm.

Tham's lawyer, Mr Selva K. Naidu, said in mitigation that an Institute of Mental Health (IMH) psychiatrist had stated that there was a "substantial causal link'' between her mental disorder - depression with psychotic features - and her offence.

It all began in mid-2013 when Tham's father stopped going to church and stopped his monthly contributions.

She felt that her father's reneging on his pledge was wrong and stepped in to assist.

She took a bank loan and paid the church eight months of contributions totalling $27,700. She took on extra duties at work to pay this off, her lawyer said in mitigation.

Three days before the incident, she forged her father's signature on a cheque for $28,030 as she felt that she had to retrieve the amount with interest from him.

This will be taken into consideration, along with another charge of being armed with a knife at the clinic.

The IMH psychiatrist had stated in an earlier report that Tham's actions did not appear to be caused by "greed, personal gain or criminogenic factors". He said: "Her actions appear to have been driven by psychotic experiences related to her religious or spiritual beliefs, which made her believe that her actions were morally correct."

Mr Naidu said his client's employer, SGH, is aware of the charges and her psychiatric condition, and has found her fit to continue her practice at the hospital.

Tham is senior consultant and director at the SGH Life Centre's Obesity and Metabolic Unit.

District Judge Mathew Joseph noted that the case was most unusual and said it was important to arrive at the right sentencing outcome. He had previously granted Tham permission to attend overseas conferences as an expert speaker. He called for both probation and mandatory treatment order reports and fixed the case for mention on Jan 6.