Reward announced in suspected murder case of Sydney woman Katrina Ploy

A $100,000 reward has been announced in the mysterious case of Sydney woman Katrina Ploy, whose body was found near a notorious suicide spot but who police suspect was murdered. 

The 25-year-old woman was last seen alive on December 17, 2006, after attending a Hawkesbury race meeting with her sister. 

Katrina Ploy's clothes, handbag and car were found on December 18, 2006. Photo: Supplied

Ms Ploy, who worked for a naval defence contractor, left her parents' house in Seven Hills that night at 5pm. 

A day later, her handbag and clothes were found at The Gap in the eastern suburbs. Her dark blue 1998-model Hyundai Excel sedan was parked nearby.

Ms Ploy's car was found parked near The Gap.  

On Christmas Day, eight days after she went missing, Ms Ploy's body was found floating in the Sydney Harbour near Lady Bay Beach. 

Following an inquest in 2010, a coroner ruled Ms Ploy did not fall 40 metres from the towering cliffs at The Gap but delivered an open finding as to the manner of death. 

"There are numerous unexplained matters at this point," Deputy State Coroner Paul MacMahon said.

"Some suspicion attaches to the death of Katrina."

Katrina Ploy (middle) a few weeks before she was found dead on Christmas day 2006. Photo: Supplied

Ms Ploy did not have any injuries consistent with falling onto rocks from a height of up to 40 metres. 

Rose Bay and Homicide Squad detectives have been investigating her suspected murder and on Monday revealed a reward for information leading to an arrest had been attached to the case.

Katrina Ploy, 25, was last seen alive on December 17, 2006. 

Police and Ms Ploy's sister will hold a media conference in Sydney on Monday morning. 

Bizarre claims from Ms Ploy's ex-boyfriend emerged at her inquest about Ms Ploy trying to organise someone to carry out her own death. 

Her former partner, Grant Millgate, told police that Ms Ploy couldn't kill herself so contacted a third party to do it for her. 

However, the coroner later found there was no substance to the claim. 

Ms Ploy was under the influence of ecstasy and alcohol before her death, the inquest also heard. 

Anyone with information can contact Crime Stoppers on 1800 333 000.