The last person to see Krystal Fraser alive saw her get into a red station wagon with an unknown man who told her "get in, get in".
Ms Fraser's friend Robert Glennie on Wednesday revealed the new information to a Victorian inquest into her 13-year disappearance from Pyramid Hill, in the state's north.
He said he did not tell police because he believed the station wagon belonged to an officer.
Ms Fraser, 23, disappeared while heavily pregnant on June 20, 2009.
She was days away from giving birth to her son and had discharged herself from hospital, telling friends she was going to a party in Pyramid Hill.
Her family fears she was murdered by her unborn baby's father.
Mr Glennie said Ms Fraser visited his house in Pyramid Hill just after 9pm on June 20, making several phone calls from his landline.
"She was scared. It's unusual for her to be there at that time of night," he told the inquest.
"It was like she was panicking. It looked like she'd been running, but I don't know for sure."
She called Alan Summers, who has since died, about seven times and then rang Jason McPherson, who was fixing her computer. Both men denied seeing her that night.
Mr Glennie said Ms Fraser left his house, crossed the road and walked in the direction of her mother's house, which was three doors down.
She walked towards a red station wagon and he heard an unknown man say to her "get in, get in".
"She did get in the car and they did leave," he said.
He did not see the man but said the car drove away and turned right at the bottom of the hill.
Asked why he did not tell police about the red station wagon, Mr Glennie said he did not trust them because he believed the car may have belonged to a Boort police officer named Ray.
"There's no other car around that looks like that," he said.
Mr Glennie said he saw a similar car had been dumped by the road in Boort some months later.
He alleged Ms Fraser told him she was "touched" by police, and had sex with an officer named Ray, believing he may have been her son's father.
"She said it's possible, she wasn't sure," he said.
"He was always chasing her ... He was definitely not a nice copper."
Several men have been named as possible fathers during the inquest, including Gareth David, who denies having sex with Ms Fraser, and Peter Jenkinson, who will give evidence on Monday.
The inquest continues.
