Two women have said they saw Tania Nicol after she is alleged to have encountered a man accused of killing her and four others, a court heard.
The five women were found dead around Ipswich in December 2006
They both said they saw the 19-year-old after she was seen on CCTV near Steve Wright's car - which prosecutors said was probably the last sighting of her.
Mr Wright, 49, denies the murder of the women at Ipswich Crown Court.
Jurors also heard a man who was freed after questioning contacted police as he feared being "another Ian Huntley".
Mr Wright's defence team told the court supermarket worker Tom Stephens admitted to detectives he would do jobs for prostitutes in return for sex and told them when questioned that if he had been the killer, he would have strangled the women.
Seen on phone
Miss Nicol, Annette Nicholls, 29, Paula Clennell, 24, Gemma Adams, 25 and Anneli Alderton, 24, were all found dead in December 2006.
The naked bodies of the women were found in and around Ipswich over a 10-day period.
The two women who said they had seen Miss Nicol both gave evidence of having seen her after 2300 GMT on 30 October - the time she was spotted on CCTV near Mr Wright's car.
Petrol station cashier Kerry Land told the court she sold a chocolate bar to Miss Nicol "some time after 11.30pm" on 30 October - a transaction that was not captured on CCTV.
Royal Mail worker Helen Brooks also told jurors she saw the 19-year-old in the Ipswich red light district, at about 0340 GMT on 31 October, talking on a mobile phone.
"The person I saw that morning was Tania Nicol," Ms Brooks said.
Jurors had earlier heard that Mr Wright's car was caught on camera heading out of Ipswich on 31 October at about 0139 GMT.
Detectives said he was heading to Copdock where Miss Nicol's body was later found.
Evidence about Mr Stephens, who was initially arrested on suspicion of the murder of the five women, was presented to the court by Mr Wright's defence team.
Mr Stephens, aged in his late 30s, was freed without charge after being questioned by detectives.
Mark Fenhalls, a member of the defence team, told the court how Mr Stephens was interviewed by police about his knowledge of all the women following his arrest on 18 December 2006.
He was arrested after he had phoned police saying he was worried about whether he had a "split personality" and whether he was "doing things which he doesn't know about, then going back to his normal personality", the court heard.
Mr Fenhalls said police had not been able to establish an alibi for Mr Stephens for any of the nights the women were said to have disappeared.
DNA samples from Mr Stephens were taken and analysed and his home and car forensically examined.
"On 21 November Tom Stephens called the police and said he did not want to be seen as another Ian Huntley and wanted to help police," said Mr Fenhalls.
"Some time after 8pm on 11 December Tom Stephens... spoke to police about the deceased women.
"He said the 'girls were all on drugs and would do anything for drugs'.
"He continued '... if it had been me, I would have strangled them'."
On 12 October police stopped Mr Stephens in his car with Miss Nicol, who he said he was giving a lift to.
"Tom Stephens said his arrangement with Tania Nicol was that he would do small jobs for her in return for sexual favours," said Mr Fenhalls.
"He saw her five to six times a week. He had similar arrangements with other girls but Tania Nicol was the most reliable and honest."
He contacted police on 1 November to say he had confidential information about Miss Nicol's disappearance, and made further calls until 9 November when he was made the subject of surveillance.
The court was also told Mr Stephens made an offer to "glean information" for the police from massage parlours, which was rejected, and neighbours reported him "hoovering his car in wet weather".
He also spent time with a BBC journalist at a pub and the following day told police in the red light district he was concerned DNA evidence might be found in his car.
Mr Stephens told police he had contemplated suicide when a national newspaper named him as a suspect.
The court also heard Annette Nicholls, one of the murdered women, told police she was raped during the summer of 2006.
Jurors were told a man was arrested on suspicion of rape in November 2006 but made no comment when questioned and the crime was marked "undetected" after Miss Nicholls body was found on 12 December.
Mr Fenhalls said the allegation had nothing to do with Mr Wright or Mr Stephens.
The trial was adjourned until Thursday.