Margaret Fleming was reported missing in October 2016 from her home but has not been seen since December 1999, when she was aged 19.
Carers Edward Cairney, 76, and Avril Jones, 58, are accused of murder, abduction, and fraudulently claiming £182,000 in benefits while living in her home.
A court has heard they claimed the benefits by pretending to Department of Work and Pensions officials that she was still living at her home, Seacroft, on Main Road, Inverkip, Inverclyde.
They are accused of assaulting Margaret between November 1, 1997 to January 5, 2000, by tying her to a chair and cutting her hair on multiple occasions.
Both face two charges of defeating the ends to justice and are accused of destroying or concealing Margaret’s personal effects between December 18, 1999 until October 26, 2017.
The other charge of defeating the ends to justice relates to trying to board a train to London from Glasgow Central Station on October 25, 2017 while carrying £3,500 in Irish bank notes, and the keys to a safe deposit box which contained £27,000.
Cairney alone is charged with assaulting another woman, Margaret Cruickshanks, on November 26, 1987, at Seacroft, by pushing her against furniture, putting his hand around her throat and repeatedly spitting in her face.
They deny all the charges.
Margaret Fleming was born on February 1, 1980, and her father, Derek, died on October 25, 1995, the High Court in Glasgow was told.
She had been photographed with the parents of Avril Jones, the second accused.
The jury was shown photographs of the squalid house where Jones and Cairney lived, on the banks of the River Clyde, neighbouring an A-road.
Many of the rooms were uninhabitable as they were stacked to the ceiling with boxes when police searched it on November 1, 2016, and a bonfire had been built in the back garden.
The white building neighboured two others on the shore of the Clyde, and another house was on the other side of the road.
Petra Sharp, scene examiner with the Scottish Police Authority, gave evidence before the court, confirming she took photographs at Seacroft between November 2, 2016 and March 2017.
She told the court: “We took photograph samples and fingerprints.”
Advocate depute, Iain McSporran QC, presented a number of images before Ms Sharp was cross examined by Cairney’s defence, Thomas Ross QC.
Ms Sharp identified a number of the rooms and cluttered hallway, including a downstairs kitchen, living room and two bedrooms.
She also confirmed the two upstairs rooms - cluttered with bags, boxes and household junk - did not look as if they were used as bedrooms.
However, she claimed they were of a size “quite possible” to be used as bedrooms.
When asked by the advocate depute if there was anything separating Seacroft from the rocky shoreline, like a fence, Ms Sharp confirmed there was not.
Discussing the rundown building, Ms Sharp noted that what stood out the most for her was a “missing bay window” on the shore side of the property.
Mr McSporran QC described the room inside as “overflowing”, with what appeared to be tools, building material and stacks of boxes.
Cairney is defended by Thomas Ross QC, and Jones is defended by Ian Duguid QC.
Judge Lord Hugh Matthews presides over the trial, which is expected to last six to eight weeks.