Detectives investigating the murder of Sabina Nessa are hunting a man seen on CCTV near the scene of her death.
The 28-year-old was discovered in Cator Park in Kidbrooke, south-east London, by a member of the public on Saturday.
Police say identifying the balding man, who was seen with something in his hands, could be “vital” to the case.
Reclaim These Streets, set up after Sarah Everard’s murder, held a vigil in Pegler Square – where the suspect was pictured – at 19: 00 GMT.
The wanted man, who was wearing grey jeans and a black jacket, can be seen looking over his shoulder and pulling up his hood as he walks along the pavement.
A 38-year-old man who was arrested in south-east London on Thursday on suspicion of murdering the teacher was released earlier on Friday, the Met Police said.
Ahead of the vigil for Ms Nessa, her sister urged people to stay safe and to pray for her.
Jebina Yasmin Islam said: “We as a family are shocked at the murder of our sister, daughter and aunty to my girls.
“There are no words to describe how we are feeling as a family at the moment. We did not expect that something like this would ever happen to us.”
Ms Nessa was attacked shortly after leaving her home in Astell Road at about 20: 30 BST last Friday.
She had been walking to meet a friend at The Depot bar, a journey that police said “should have taken just over five minutes”.
Her body was found the next day near a walkway in the park.
Metropolitan Police Assistant Commissioner Louisa Rolfe said the force was not asking women to change their behaviour when going out at night.
It comes after information sheets advising women on how to stay safe at night were handed out by a community group.
“It’s really important to us that we don’t ask women to change their behaviour,” she said.
“Violence against women and girls is a priority for police across the UK but we’re really conscious that women should be free to go about their lives without fear of abuse.”
She added that violence against women had the “hallmarks of an epidemic”.
“It is something that is tolerated far too much in society and we the police are determined to bring offenders to justice and to prevent these offences where we can,” she said.
She asked anyone with information about Ms Nessa’s death to come forward.
The Duchess of Cambridge has said her thoughts are with the family and friends of Ms Nessa and that she is “saddened by the loss of another innocent young woman on our streets”.
Ms Nessa was a teacher at Rushey Green primary school in Catford.
The head, Lisa Williams, called her “a brilliant teacher” adding that she was “kind, caring and absolutely dedicated to her pupils”.
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