A probe into the death of a 'happy, bubbly' mother and her three children has taken a new twist as police revealed details of a 'stabbing incident' hours before she died.

Fiona Anderson, 23, is thought to have fallen to her death from Battery Green multi-storey car park in Lowestoft, consistent with post-mortem results. She was formally identified last night.

But in a new development, police revealed they attended an address in London Road South, where she lived, hours before her death.

Det Supt John Brocklebank, of the Norfolk and Suffolk Major Incident Team, said officers were first called to a 'stabbing incident' in Mill Road at 8pm on Sunday.

They found reports that a man had been stabbed were false, but in the 'early hours' of Monday morning attended an address in London Road South.

A 23-year-old woman who has since died – understood to be Miss Anderson – spoke to officers via the intercom, and refused them entry.

Det Supt Brocklebank said officers did not pursue a warrant and left the address.

He confirmed a 'stabbing incident' had taken place with a male victim but would not comment on the exact timing or the extent of injuries to the unnamed male.

It is understood that Miss Anderson had spilt up with partner Craig McLelland, father of her children, before her death, but Det Supt Brocklebank would not comment on the identity of the victim.

He refused to comment on whether the incident was 'an opportunity missed' – but it has been referred to the IPCC for investigation.

Miss Anderson was spotted on CCTV walking around north and south Lowestoft after the incident, wearing a light-coloured coat and carrying a teddy bear.

She was found at the foot of the multi-storey at around 8am – five minutes after CCTV footage showed her entering the multi-storey off Gordon Road.

Her three children Levina, three, Addy, two, and Kyden, 11 months, were found dead hours later at Miss Anderson's basement flat in London Road South.

The time and circumstances of their deaths has yet to be revealed.

A post-mortem was carried out on the three children at the James Paget University Hospital (JPH) but the cause of death was unascertained in all cases and further tests are to be conducted.

Police are treating all three of the children's deaths as suspicious.

Stunned friends are still struggling to comprehend the four deaths.

Megan Smith, 19, was Miss Anderson's next door neighbour and had known her since her school days.

Miss Smith attended Foxborough Middle School, next to Miss Anderson's school Benjamin Britten, and the pair 'used to walk everywhere together'.

'She was a happy, bubbly person –always smiling,' said Miss Smith. 'You wouldn't have thought she was depressed if you saw her out in the street.

'She was brilliant as a mum, you couldn't fault her.

'She was as close to perfect as you can get.'

But she said life was not always easy for Miss Smith, who had a lot of responsibilities for a woman so young.

'She had three kids and one on the way and some rough patches,' she noted.

Miss Anderson was heavily pregnant with a fourth child, who she had hoped to name Evalie.

Neighbour Karleigh Burlingham, 20, said Fiona was a 'brilliant' mum.

'She was outgoing and a lovely person – a diamond,' she said. 'She was a brilliant mother to those kids –you couldn't fault them one little bit.'

She added Miss Anderson was 'more of a night person' and they enjoyed late shopping trips to Asda together.

And she cannot put her finger on anything that caused the tragedy.

'I hadn't noticed any change,' she said.

Leon Cook, 18, knew Miss Anderson and is also friends with her partner Craig McLelland, who is the father of the three dead children.

'Those kids got whatever they wanted from both of them,' he said. 'I didn't see anything wrong.'

He said he lived with Miss Anderson in Gunton for about three years and found her to be 'a lovely lady'.

And he said Mr McLelland –'a great lad' – had been in a relationship with her for almost six years.

The eldest of the three children – Levina – attended pre-school at Fen Park Community Primary School.

And the tragedy has hit everybody there hard.

Heather Madsen, headteacher of the school in Southwell Road, said: 'This is an extremely sad situation and one that has touched the whole school community.

'We've put appropriate support in place for parents and staff who may need it.'

Staff were moved to add to the tributes outside the flat in London Road South.

They wrote: 'To our poor babies. Always in our thoughts. Fly high and be with your mummy x x x x x'.

And ripples have also been felt in the wider community, by people who did not know the family personally.

Gary Keyzor, chairman of Lowestoft Town FC, said the club is hoping to record a minute's silence at its next home fixture on April 27.

'It's something we will look at as a mark of respect,' he said.

'I'm sure it's something the team would get behind.'.

Last night, Kirkley and Pakefield reserves and K&P's B team were playing two matches at their Walmer Road ground and observed a minute's silence before them.

Barrie Atkins, steering group member, said: 'We, as a community club, send our condolences to the family and friends at this sad time and they are in our thoughts.'

Members of London Road Baptist Church, and Whitton Life, will be opening up The Archway, opposite the KFC drive-thru restaurant today (Wednesday) and tomorrow (Thursday) from 9am to 6pm.

A spokesman said: 'So that friends family and any members of the community affected by this loss can meet to chat, grieve, have a cuppa, pray and pay tribute. At times like this we need each other, don't be shy.'

And tributes continued to pour in last night.

Among them, 'Cassie and Logan' wrote: 'I'm sorry you couldn't fight those demons.'

sam.russell@archant.co.uk