An extensive three-day search was launched on Friday for Jessica Zrinski, who is described by family members as friendly and approachable.
The 30-year-old has not been seen since November 28, when CCTV captured her getting into a car in a hotel car park at Greenfield Park in Sydney's west.
The images show Ms Zrinski being driven away in a blue Holden Commodore station wagon, which was later spotted driving along the M4 and Great Western Highway towards the Blue Mountains.
Homicide squad commander Detective Superintendent Danny Doherty said the new police search would focus on the Hampton State Forest about 25km north of Jenolan.
"We believe Jessica may have entered or visited the Hampton State Forest sometime after she was last seen entering the Holden Commodore station wagon in late November," Det Supt Doherty said.
"Our investigators are conducting this search to find some trace that Jessica may have been here and will leave no stone unturned in our quest to locate her."
He urged anyone with any information about Ms Zrinski's whereabouts or the car she was last seen in to contact police.
Volunteers will join officers from PolAir, the dog unit and other police units for the search that will run until late on Sunday.
Det Supt Doherty said detectives were pursuing all lines of inquiry including the possibility Ms Zrinski met with foul play.
She was last seen by family members in the Bossley Park area on the day before she got into the Commodore, and was reported missing on December 3.
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