A father of three who killed his autistic daughter before jumping to his death in August last year had a history of depression, bipolar mood disorder and delirium.

Mr Tang Soh Ha, 69, who was Ms Tang Hui Yee's primary caregiver, was also suffering from insomnia.

In an inquiry into their deaths yesterday, State Coroner Kamala Ponnampalam said Mr Tang was having suicidal thoughts shortly before the tragedy.

She added: "When he was unable to sleep, Mr Tang would lie awake worrying about Ms Tang's future.

"His declining health caused him grave concern about Ms Tang's care arrangements."

The State Coroner found that Mr Tang had fatally assaulted his 27-year-old daughter with a knife before taking his own life by jumping from Block 560, Pasir Ris Street 51 on Aug 20 last year.

She noted Ms Tang was a student at the Movement for the Intellectually Disabled of Singapore school and was known to become agitated when her demands were not met.

Ms Tang also had frequent episodes of aggression during which she would hit and push others, she added.

Her father, on the other hand, had been treated for depression in a Thai public hospital in 2005. He was first seen at Singapore's Institute of Mental Health (IMH) three years later due to acute behavioural changes following the failure of his business in Bangkok.

He was treated with mood stabiliser medication and, according to family members, he remained symptom-free from any depressive or manic conditions.

On Aug 5 last year, Mr Tang went to IMH following a referral by a polyclinic for having suicidal thoughts. State Coroner Kamala said Mr Tang's case manager from IMH contacted him 11 days later.

She added: "He said that his mood was low in the morning and he was having worries such as the future of his intellectually disabled daughter. He also reported having suicidal thoughts again."

Mr Tang was advised to go the IMH emergency room for an early review if he felt suicidal or unable to cope with his symptoms.

However, one of his neighbours found him lying motionless at the foot of their block at around 1.20pm on Aug 20 last year and alerted the police. He was pronounced dead about 10 minutes later.

Closed circuit television footage taken from a lift at the block showed him going up to the eighth storey alone at 1.14pm.

His family members later accompanied a police officer to their home on the second storey and spotted Ms Tang lying face down in the kitchen with deep wounds at the back of her neck. She was pronounced dead at 2.22pm.

Their family members were not in court yesterday.

HELPLINES

SAMARITANS OF SINGAPORE: 1800-221-4444

SINGAPORE ASSOCIATION FOR MENTAL HEALTH: 1800-283-7019

INSTITUTE OF MENTAL HEALTH: 6389-2222

CARE CORNER COUNSELLING CENTRE (Mandarin) : 1800-353-5800