Four traces of unknown men were found in the apartment of Susan Christie after she disappeared, a government forensic scientist told the Supreme Court this week.

Traces of DNA were on the lounge carpet, along with the blood of Mrs Christie, a ring and watch owned by Mrs Christie and the handle and trigger of a Spray 'n' Wipe bottle found in the bathroom, Dr Laurance Webb told the Supreme Court.

There was also no match with the 50,000 people on WA's database, or on those of jurisdictions with which WA has a sharing agreement - Queensland and the Northern Territory.

A weaker profile appeared for Gregg Baird, a man the couple upstairs had contacted through a swingers' magazine the night Mrs Christie was last seen.

Elements of the DNA of Peter Finn, one of Susan Christie's lovers, was found on a piece of clothing, a black top found on the floor, and a fragment of glass.

He said it might be possible to eliminate DNA by cleaning, but the cleaning agents needed were so strong that they were likely to damage the interior of a car.

This is cache, read story here