Police today arrested a 38-year-old man on suspicion of murdering Sabina Nessa in a 'significant development' in the investigation.
The man was arrested on suspicion of murder at around 3am today at an address in East Sussex and taken into police custody.
Meanwhile, detectives believe the primary school teacher may have been bludgeoned to death with a red can of fizzy drink, The Mail on Sunday revealed.
CCTV footage which has not yet been released by police reportedly shows her attacker strike her over the head with an object before carrying her over his shoulder towards the park where her body was later discovered.
A police source said officers believed the red item was an 'object like a drinks can'.
Of the latest arrest, Detective Chief Inspector Neil John, from the Met’s Specialist Crime Command, said: 'Sabina's family have been informed of this significant development and they continue to be supported by specialist officers.'
Sabina Nessa, 28, originally from Bedfordshire, disappeared on September 17 as she left home to meet a man for a first date at a local pub and her body was found the following afternoon
Detectives are also urging people who were driving in the area on Friday night to check their dashcam footage for possible glimpses of the suspect in the car headlights.
The 28-year-old's killer remained at large last night but a police source said a man caught on security cameras carrying a 'red reflective item' is their prime suspect.
Murder detectives believe they have identified the man in the footage and were urgently trying to find him.
Police yesterday reissued footage of the man, who was seen on CCTV in Pegler Square in Kidbrooke, South East London.
The force said the images were captured 'shortly before' Sabina's murder. In the grainy film, the man is seen carrying something red in his hands.
The new information came as Home Secretary Priti Patel admitted women survivors of violence were being 'let down' by police.
Ms Patel said cases of violence against women were still 'far too common' and that she was 'carefully considering' moves to tackle the problem, the Times reported.
The Home Secretary's remarks came hours after the Metropolitan Police insisted the area where Ms Nessa was killed was still 'safe for women'.
Detectives are urgently to appeal for information about a mystery man who was captured on CCTV in Pegler Square, south east London, on the night Sabina, 28, was attacked
Police comb the area around Pegler Square in Kidbrooke, south London, searching for evidence in the alleged murder of 28-year-old Sabina Nessa
Detective Chief Inspector Neil John, from the Met's Specialist Crime Command, said: 'People in the Kidbrooke area last Friday may recall seeing this man carrying a red reflective object, and possibly trying to conceal it.
'Please share the CCTV footage on social media and show the image to family members and friends who may not have seen it. He must be traced.'
Forensic officers scoured an area of Pegler Square on Friday evening. It's understood that they were looking for the potential murder weapon.
Ms Patel has said is considering recommendations to help tackle violence against women because these things 'should have no place' in our society.
She singled out crimes such as 'rape, female genital mutilation, stalking and harassment' which are taking place every day.
'These crimes are still far too common and there are too many instances of victims and survivors being let down.'
'The tragic cases of Sarah Everard, Julia James, Bibaa Henry, Nicole Smallman and Sabina Nessa demonstrate this.'
The Victims' Commissioner has urged the police to do more to make streets safe for women in the wake of the killing.
It also emerged yesterday that parents at Sabina's Rushey Green Primary School had received a warning letter several months ago about a string of attempted abductions by strangers.
Lewisham police issued the alert in May following the reports that four children had been approached by unknown men in neighbouring Bromley.
Ms Nessa had been working at the school in Catford, which has 600 pupils and around 70 staff, for just over a year after she qualified last year.
A teacher at the school said: 'The Year Two pupils, who Sabina taught last year in Year One will be the most upset, and their parents. It is hard for teachers to reassure children who are nervous about being at school for the first time, while they are putting on a brave face while consumed with grief themselves.'
Sabina left her flat in Kidbrooke to meet a man for a first date at the nearby Depot bar at around 8.30pm on Friday, September 17. She never arrived there.
Her body, which had been covered with leaves, was found the following evening by a dog walker near the OpenSpace community centre in Cator Park, less than 500 yards from the victim's front door.
Meanwhile, more than 500 well-wishers, including Ms Nessa's sister Jebina, gathered in Pegler Square for a vigil on Friday, organised by campaign group Reclaim the Streets, which said it is 'angry and heartbroken' about her death.
And teachers at Rushey Green Primary School in Catford, where Ms Nessa worked, said they are 'consumed by grief' following their colleagues death, but said they are putting on a 'brave face' for their students.
Teachers at Rushey Green Primary School in Catford, where Ms Nessa (pictured) worked, said they are 'consumed by grief' following their colleagues death
Police stand guard near Pegler Square in south London the night after a vigil for killed primary school teacher Sabina Nessa
Primary school teacher Ms Nessa, 28, originally from Bedfordshire, disappeared on September 17 as she left home to meet a man for a first date at a local pub, The Depot
More than 500 well-wishers, including Ms Nessa's sister Jebina, gathered in Pegler Square for a vigil on Friday, organised by campaign group Reclaim the Streets, which said it is 'angry and heartbroken' about her death
One teacher at Ms Nessa's, who did not wish to be named, said it was awful to think that the 'kind and dedicated' teacher had 'suffered in the most violent way' and said the staff are all rallying around to support each other.
They told South London Press: 'No one and nothing can prepare you for this - the first anyone knew was when we arrived at school on Monday morning.
'It is awful enough when someone dies. This is so much worse. It is impossible to even comprehend - that she suffered in the most violent way. We were sitting beside her on Friday - then this.
'The Year Two pupils, who she had last year in Year One, will be the most upset - and their parents.
'Everyone is supporting each other. But it is hard for teachers to reassure children who are nervous about being at school for the first time - while they are themselves putting on a brave face while consumed with grief themselves.'
Ms Nessa had just taken on a new Year One class for the start of term at the school, which has 600 pupils and around 70 staff.
Lisa Williams, headteacher of the school, has spoken to classes individually with educational psychologists also offering help.
Speaking of her 'devastation' after Ms Nessa's death, she told Sky News: 'She was a brilliant teacher; she was kind, caring and absolutely dedicated to her pupils.
'She had so much life ahead of her and so much more to give and her loss is desperately sad.
'As a school we are supporting each other through this very difficult time.'
Ms Nessa was a member of the National Education Union's Lewisham branch, which held a minute's silence at a meeting on Wednesday night and has written to the school.
Branch secretary Duncan Morrison told the South London Press: 'Staff would be given the opportunity to reflect and spend time thinking about Sabina. We would always try to listen - the last thing people in shock or grief want is to be told what to do.
Meanwhile, a vigil took place in Peglar Square, near to where Sabina's body was found, at 7pm on Friday. Pictured: Jebina Nessa pays tribute to her sister during the vigil
Sister Jebina Nessa broke down in tears as she paid tribute to her sister Sabina, a 28-year-old primary school teacher who was murdered yards from her south east London home
People look at floral tributes for murdered 28-year-old teacher Sabina Nessa in Kidbrooke in south-east London ahead of a vigil tonight
'It is hard even for an adult to comprehend what seems to be the senseless murder of a young woman. Her pupils are so young, which makes it all the more difficult. It is hard even to explain to the oldest children at a primary school.
'She was only just starting to build relationships with the new Year One children. The class which will experience it most will be those she taught last year. She had a strong relationship with them.
'The crucial thing is to give them space to feel what they are feeling. But at that age, they have limited language to express it. We would say it is OK to cry and share your feelings - but if they do not want to, that's fine too. It is a terrible thing to deal with.'
Meanwhile, the Victims' Commissioner for England and Wales has urged police to do more to make the streets safer for women.
Furious campaigners and a handful of MPs have demanded that public spaces be made safer for women in the wake of a string of high-profile murders this year.
Parallels are being drawn to the horrific murder of 33-year-old marketing executive Sarah Everard in March, amid fresh fury that women could not walk through Britain's streets alone without fearing for their lives.
Detective Chief Superintendent Trevor Lawry insisted the area remains 'safe for women' despite mounting pressure from women's safety campaigners who are urging officers to do more to protect them on Britain's streets.
But Dame Vera Baird, who attended a vigil to the murdered 28-year-old in Wood Green, north London, on Friday, argued there needs to be more onus on police to protect the public than on women to take precautions.
She told BBC Radio 4's Today programme: 'Apparently the police have been giving out rape alarms to women and giving leaflets out saying how to stay safe in a public place.
'It is less, isn't it, about giving women leaflets on keeping themselves safe in dangerous places and more about the police making the streets safe for women?'
When it was put to her that there needed to be societal change along with police intervention, Dame Vera replied: 'It certainly isn't just a job for the police but, look, the police do have a very key role here.'
She added: 'Three-quarters of women over 16 have been harassed in a public place and don't feel safe.
'They need to know that the police understand that and will use all the powers they have got to keep the streets safe.'
Hundreds of mourners, including Ms Nessa's sister Jebina Yasmin Islam, attended an emotional candlelit vigil in Pegler Square, Kidbrooke, south-east London, where she had been heading to the pub on the evening she was killed.
Jebina broke down in tears as she paid tribute to her sister and addressed crowds at the vigil, saying her world had been completely 'shattered' following the loss of Sabina.
A separate rally earlier in the evening at East London Mosque heard powerful testimony from other members of Ms Nessa's family.
It comes as police are understood to believe the prime suspect in the Sabina Nessa murder is still at large after releasing two men they had arrested for the teacher's killing.
Detectives are appealing for information about a man who was captured on CCTV in Pegler Square, south east London, on the night Sabina, 28, was attacked.
Two men who were arrested in connection with the alleged murder have been released under investigation, the Metropolitan Police confirmed.
Sabina left her home on Astell Road after arranging to meet a friend at The Depot bar in Pegler Square, Kidbrooke Village, south-east London, last Friday night but never made it.
