A young mother who lost her baby girl in suspicious circumstances was seen cradling a teddy bear as she left her home after a visit by homicide detectives on Wednesday.

Emergency services were called to a property on Leith Street, in Redan, just south of Ballarat, on Sunday where an eight-month-old baby was found unresponsive.

Paramedics attempted to revive the child, performing CPR before taking her to a hospital in Ballarat just after 1pm. 

She was later rushed to a Melbourne hospital where she died on Tuesday.

Police revealed homicide squad detectives have interviewed a 23-year-old man who was later released pending further inquiries.

On Wednesday morning, the Daily Mail observed plain-clothed detectives visit the home before promptly leaving. 

The infant's mum was seen at the door holding the child's toy before leaving soon after accompanied by another man. 

Neighbours told the Daily Mail the couple pictured had lived at the rented three-bedroom bungalow for under a year and had rarely been seen outside. 

When the tragedy unfolded on Sunday, one neighbour revealed the young man seen on Wednesday did not go with the police and travelled with the child to hospital.

'He went with an ambulance 4WD, so he wasn't detained or anything,' the neighbour added.

It is not suggested that either the mother or the man shown are in any way suspected of being involved in relation to the death. 

Locals saw paramedics rush to the quiet street around midday on Sunday, followed 30 minutes later by a fleet of police cars.

They established a crime scene and began going door-to-door asking for information on the couple. 

'Detectives and just regular cop cars arrived,' said one resident. 'Probably about four regular cop cars. They even had the fire brigade as well. 

'They had about four ambulances. It  was crazy, and then they had a cop sitting in the driveway for two days, just watching.'

Police issued a statement on Tuesday night with an update on the ongoing investigation, confirming it was being treated as suspicious by homicide detectives.

'The exact circumstances are yet to be determined and detectives from the Homicide Squad will investigate,' a police spokesman stated.

Neighbours said they knew little about the family at the $400-a-week home and said they had been an enigma in the close-knit street. 

'I don't think I've ever seen them,' one neighbour said. 'I know most of the neighbourhood but I've never seen those two.'

Another added: 'I didn't even know they had a baby or anything. Didn't even hear cries or anything.' 

One neighbour said she had been asked by the couple to check on their mail while they went on a dream trip to the US soon after they moved in. 

'They just said, "Look, we're heading off to America over Christmas" last year, and asked if we could keep an eye on the mail, so that's what we were doing,' she said. 

The neighbour only knew there was a baby living in the home because she could see the child's cot from her yard. 

The local thought the man may have worked at McCain's frozen food plant in nearby Wendouree.

'They keep to themselves, she added. 'I don't even see them in the backyard or anything like that and I've caught them from the window where I am across. 

'I knew there was a baby there or a young child.' 

The neighbourhood was usually quiet and peaceful and locals considered it perfect for bringing up a young family. 

'It's all very sad. Whatever the cause, a baby has died and we're all just in shock that it has happened here,' one woman said. 

'We had thought it maybe wasn't suspicious after all because we hadn't seen a single reporter out here since it happened [until the Daily Mail arrived].' 

The couple declined to comment when approached by the Daily Mail on Wednesday. 

Police have asked anyone with information to call Crime Stoppers on 1800 333 000 or visit www.crimestoppersvic.com.au. 

READ MORE: Gus Lamont's heartbroken parents speak out for the first time as cops reveal new 'anomalies', offer $1million reward and confirm grandparent remains a suspect