Mother suspected of stabbing children was 'suffering from post-natal depression' says friend

Sasikala Navaneethan's six-month-old daughter is fighting for her life after the attack at the family home in which her five-year-old brother and four- year- old sister were stabbed to death.

Last night she was detained under the Mental Health Act.

The 35-year-old Sri Lankan-born mother was described as a 'devoted' parent but struggling to cope with the emotional and financial pressures of bringing up a family.

Little victim: The six-month-old, pictured just after birth, whose brother and sister were stabbed to death in their bedroom

She and her husband Navarajah, 39, often worked 14 hours a day, seven days a week, running a convenience store which had recently suffered a loss of business because of a new bypass.

Mr Navaneethan was also originally arrested on suspicion of killing his son Shanjayan and daughter Sharani, but was yesterday released without charge over the attacks. He remains on bail over another allegation.

It was Mr Navaneethan who found the children's bodies in a bedroom after returning to the family's £356,000 detached home in Carshalton, South London, on Friday evening.

Tributes: Flowers were left by well-wishers outside the house

Jay Raman, a friend of the couple who owned a business next to their grocery shop, said: 'They both loved their children and were devoted to them.

'But things were getting too much for her, running the business and raising the family.

'She had failed her driving test, which didn't help. They'd been trying to get things together and make life easier for themselves. They moved from the flat above their shop to the new house to have more space'.

Mr Raman, 36, who has known the couple for four years, said the children were 'well-mannered and well-behaved.' He said: 'The boy was always riding up and down on his bike. You couldn't get him off it.

'They were brought up as you would want a child to be brought up. But they were very shy  -  the parents once had trouble getting the boy into the car to come home with me because he didn't like to be away from them.'

Mrs Navaneethan rang 999 at 10.30pm on Friday and was put through to an interpreter because of her poor English.

Neighbours said a fleet of police cars and ambulances arrived soon afterwards and brought out the 'limp little body' of one child, wrapped in a blood-soaked sheet.

Their mother was later led from the house in handcuffs. Mr Navaneethan was seen pacing the street before being taken away in a police van. The two older children died later on Friday.

The baby, said to have had her throat slashed, is in critical condition at St Thomas' Hospital in Central London. Her name has not been released.

Friends said the Tamil couple had lived in Britain for at least seven years. Jane Quaintance, who runs a bar next door to their shop in Coulsdon, Surrey, said: 'I spoke to him on Friday as he was about to go home. He seemed very happy. The poor man obviously had no idea what was waiting for him.'

Sutton Council said its social services department had had no contact with the family.

• A 35-year-old woman has been detained under the Mental Health Act over the attacks, Scotland Yard said last night. She will be taken to a secure unit.

Sealed off: the three-bedroom house was cordoned off as forensic teams worked inside