A physics professor and a leading underwater pathologist used by police in the Caroline Byrne ''model-off-The Gap'' murder investigation will be called to give evidence at the inquest into the death of Katrina Ploy at the same location in 2006.

Like the death of Miss Byrne, which led to the conviction of her boyfriend Gordon Wood, police do not believe Katrina Ploy, 26, jumped to her death from the same Watsons Bay cliff top.

They suspect Miss Ploy's handbag and jacket, found next to a fence on the northern end of a cliff at The Gap on December 18 that year, was placed there by another person in an effort to make her death appear as if she took her own life.


Tragedy ... Katrina Ploy.
Police also have concerns that Miss Ploy's body did not have injuries consistent with having fallen between 33 and 35 metres into the ocean.

''Poor Katrina Ploy - she hasn't got a mark on her body or any internal injuries or broken bones,'' Detective Sergeant Paul Quigg said yesterday.

Sergeant Quigg, a homicide squad investigator on the Caroline Byrne case, was asked to consult with Rose Bay police to investigate the death of Miss Ploy, whose body was discovered floating in the water off Lady Bay beach on Christmas Day, 2006.

How her body came to float north from The Gap, into the harbour against southern currents, has heightened police suspicions of foul play.

''A post mortem found that she drowned and there was no sign of broken bones or even internal damage to any of her organs, which one would expect from impact hitting water from such a height,'' Sergeant Quigg said. He said Strike Force Beveridge, formed to investigate the Parramatta woman's death, had consulted Queensland University professor Tony Ansford, an underwater pathologist, who told them the lack of any injury to her body was highly suspicious.

Sydney University associate professor in physics Rod Cross, who gave evidence in the Byrne case as to whether her body was thrown out onto rocks at The Gap, was also consulted.

Sergeant Quigg said the reason Miss Ploy made six trips to, and from, Watsons Bay in the days before her death, remained a mystery.

She made three of the journeys in taxis and the rest in her blue 1998 Hyundai Excel sedan, which was found parked near the Watsons Bay Hotel shortly after her bag and jacket were located about 1am on Monday, December 18.

''We think she may have been using a second mobile phone, which has not been found,'' Sergeant Quigg said.

''The taxi drivers said she was talking to someone who she was going to meet at Watsons Bay.

''Her work clothes on a hanger were folded neatly in the boot of her car so it is possible she went to Watsons Bay on December 17, with the intention of spending the night with someone and then going to work the next day.''

With an inquest into the death due to begin before Deputy State Coroner Paul McMahon at the Coroners Court, Glebe, on August 2, police are renewing appeals for public assistance from anyone who saw Miss Ploy at Watsons Bay.

''Police had received information that she might have visited a tattoo parlour on the Great Western Highway before her death.