CCTV footage has been released showing an aspiring model enjoying a night out hours before she was murdered.
The images show Sally Anne Bowman, 18, with friends in Lloyds Bar, Croydon, south London, on 24 September.
Detectives showed the CCTV on the BBC's Crimewatch programme on Wednesday as they made an appeal for information.
Miss Bowman was sexually assaulted and stabbed several times after being dropped off at her home. Her body was found in the early hours of Sunday.
The CCTV footage followed Miss Bowman as she bought drinks at the bar, chatted with friends then left with her sister at 0100 BST before going to a friend's house.
At 0200 BST she is seen coming back into town in a taxi and about 20 minutes later her ex-boyfriend picks her up and drives her home to Blenheim Crescent, South Croydon.
Miss Bowman's sisters Danielle and Nicole appeared on the programme alongside Det Ch Insp Stuart Cundy, who is leading the murder investigation.
Danielle, who had dropped Miss Bowman in Croydon the night she was killed, said her sister was looking forward to a night out.
"She couldn't wait to go home and get ready and choose the outfit for the evening ahead of her," she said.
The suspect is white, in his 20s or 30s, with short brown hair
"Sally was the best sister, daughter and aunt you could possibly wish for.
"She was a beautiful young woman, inside and out, and she was just like any other typical teenager... and we all miss her dearly."
Earlier police released an image of a man suspected of killing Miss Bowman and a £20,000 reward was offered for information leading to a conviction.
It is thought the killer lives or works locally and police said they may carry out DNA tests on men under 40.
Det Ch Insp Cundy believes the man they are looking for is a serial sex attacker who may have committed about six other assaults.
Miss Bowman's murder has been forensically linked to a sex attack in nearby Purley in 2001.
Lying in wait
It is thought the same man also attacked and robbed another woman just hours before killing the model.
DCI Cundy showed a white handbag, mobile phone, cardigan and purse similar to those taken from Miss Bowman.
He also said it was likely her attacker had probably been lying in wait and that "someone might have seen him and not realised how significant that was".
The attacker is described as white, in his 20s or 30s, between 5ft 9in and 6ft and of medium build with short brown hair.