A mother who stabbed her three children to death after fearing she would lose them was jailed for 16 years today.

Theresa Riggi, 47, killed her twins Austin and Luke and her daughter Cecilia at their Edinburgh home last August.

The children were born in Norwich and their parents had lived for several years at Corton, near Lowestoft.

The youngsters' bloodstained bodies were discovered lying side by side at the Slateford Road townhouse following a gas explosion at the building, each with eight stab wounds and multiple cuts and bruises.

American Riggi was found badly hurt after plunging from a second-floor balcony in an apparent suicide bid. She also had stab wounds which were believed to have been self-inflicted.

She was initially charged with murder but last month admitted three counts of the lesser charge of culpable homicide on the grounds of diminished responsibility.

She was sentenced today at the High Court in Glasgow after Donald Findlay QC spent more than two hours delivering a plea of mitigation on her behalf.

Lord Bracadale, on sentencing, said: 'You have pled guilty to charges of repeatedly stabbing to death each of your twin sons, Austin and Luke, aged nine years, and your daughter Cecilia, aged five years.

'The result of these acts is a devastating family tragedy. The father of the children, Pasquale Riggi, and the wider family have been left utterly bereft by the loss of the children.

'And you, who had a genuine but abnormal and possessive love of your children, have lost them and are brought to this sorry pass.'

He added: 'You, and others, must understand that while your responsibility is diminished, you are still responsible for your actions.

'The effect of the diminished responsibility is to reduce these crimes from what would have been exceptionally wicked crimes of murder to what are still very serious crimes of culpable homicide.

'The number and nature of the stab wounds to each child is indicative of a truly disturbing degree of violence which, in order to bring about the deaths of three children, must have been sustained over a significant period of time. It is difficult to envisage the physical commission of such acts.

'It is clear that any degree of responsibility for such ghastly and grotesque acts must be visited with a lengthy sentence of imprisonment.'

TThe court was told previously that Riggi and her estranged husband Pasquale, a Shell UK engineer, had been involved in a legal action over the children's custody at the time of the killings.

Alex Prentice QC, prosecuting, said they had been due to appear at a hearing the day before the youngsters' deaths.

Days before the killings, Riggi told a friend things were so bad he would 'hear about it on the national news'.

On the evening of August 2, Riggi spoke to her husband on the phone. Mr Prentice said she accused him of being in collusion with their solicitors and asked if he would take the children away.

On being told she 'left him no choice', Riggi replied 'say goodbye then' and hung up.

The court heard that the bodies of the three children were found by building manager Derek Knight on the afternoon of August 4, following a loud explosion at the property.

Harrowing details of their discovery were revealed for the first time in court last month.

The court heard how a neighbour, Jordan Cochrane, saw Riggi climb on to the balcony after the blast before 'intentionally' falling head first.

He managed to break her fall but she was found to have four or five stab wounds, a collapsed lung, cuts to her neck and wrist and fractures.

Inside the property, Mr Knight stepped over the bodies, opened the curtains and saw Riggi lying on the ground.

Another witness saw Riggi shouting and screaming something like 'I can't believe this has happened to me', the court heard.

Paramedics who went to the scene believed the children had been dead for some hours.

When police entered the house they saw the three children lying side by side on the bedroom floor. They also found three knives nearby, each covered in blood, and noted large amounts of blood in numerous places throughout the house.

Officers also found a song similar to that heard at church services was playing on a laptop. It was called Angel and the artist was 'Tess Riggi'.

Pathologists found all three children had multiple bruises and abrasions and died of stab wounds to the chest.

At the previous hearing in March, the court heard that both Riggi and her husband, although separated, were living in Aberdeen before Riggi took the children to live at the Slateford Road property last summer, unknown to Mr Riggi. The couple had previously lived together in the US, the Netherlands and Lowestoft. Mr Riggi has worked for Shell since 1987 and the family came to the UK 10 years later. He was based at Shell in Lowestoft from 1997-2002. During this time the family are believed to have lived at Corton, but the children are believed not to have attended any of the local schools, being taught at home.

Outside court, Mr Riggi stood as a statement was read out on his behalf. It spoke of his 'wonderful, energetic, bright and happy' children who were taken away by a 'selfish, brutal and murderous' act.

In the statement read by David Sinclair, of Victim Support Scotland, Mr Riggi said: 'I will never forget Austin, Luke and Cecilia. They left everlasting impressions on me. I think about them at least 100 times each day. They are in my thoughts when I wake in the morning and before I go to sleep at night.

'They were such wonderful energetic, bright and happy children. Those of us who had the pleasure of knowing Cecilia, Luke and Austin, looked forward to watching them grow while they independently navigate through their unique life journeys.

'We are so thankful for the opportunity we had to know and love them and the memories that we made together, allowing us to cherish them so dearly now.'

He added: 'The horrific manner in which my children died will leave an indelible mark on the rest of my life. As a father, my natural instincts were geared towards safeguarding my children from the dangers of this world.

'It pains me to the core that I was unable to protect them from the selfish, brutal and murderous act that ended their lives so unfairly.

'There is no justification for this heinous crime, repeated three times, nor is there any sentence that can provide justice for the overwhelming loss of three lives and the subsequent painful grief and devastation caused to surviving family and friends.'