– With AAP

A man believed to be the ex-boyfriend of murdered Sydney dentist Preethi Reddy died a day before her body was discovered stuffed inside a suitcase.

Harsh Narde is suspected of murdering Reddy, his ex. He was also a dentist.

Investigators found Dr Reddy dead in her grey Volkswagen Golf on Strachan Lane in Kingsford east of the city about 9.30pm on Tuesday. She had been stabbed “numerous times”.

The gruesome discovery came just hours after police issued a public appeal to find the 32-year-old from Penrith.

Dr Reddy was reported missing on Sunday after she failed to return home following a dental convention at St Leonards over the weekend.

She was captured on CCTV inside McDonald's at the Strand Arcade in Sydney's CBD about 2.15am on Sunday - the last time she was seen.

She was standing alone, wearing a dark-green long-sleeved top, black pants, and black ballet flats. She appeared to leave alone.

She last spoke with her family about 11am that morning, saying she planned to head home after having a late breakfast.

Friends and family had "serious concerns for her safety" as her disappearance was out of character.

NSW Police detectives now believe Dr Reddy stayed at a hotel on Market Street on Sunday "with a man known to her".

Dr Narde is believed to be her former boyfriend who was also attending the dental conference, a police source told AAP.

Women and Violence: The Hidden Numbers. Post continues after video.

It's unclear whether they were intimately involved or not.

Police spoke to Dr Narde about Dr Reddy's disappearance before he was found dead on the New England Highway at Willow Tree, south of Tamworth, about 10pm on Monday.

Police have since identified that his death was intentional.

Dr Reddy worked at Glenbrook Dental Surgery in the lower Blue Mountains.

"Glenbrook Dental Surgery staff are in mourning to hear the sad news about Preethi Reddy," her colleagues posted on Facebook on Wednesday.

On Tuesday, her colleagues told the ABC they were "terrified" and had been unable to sleep since her disappearance.

The dental surgery was closed on Wednesday.

A Facebook page was set up soon after Dr Reddy went missing, calling for people to "help find Preethi Reddy".

The page has not been updated since Reddy's body was discovered.

If this post brings up any issues for you, or if you just feel like you need to speak to someone, please call 1800 RESPECT (1800 737 732) – the national sexual assault, domestic and family violence counselling service. It doesn’t matter where you live, they will take your call and, if need be, refer you to a service closer to home.

If you think you may be experiencing depression or another mental health problem, please contact your general practitioner or in Australia, contact Lifeline 13 11 14 for support or beyondblue at 1300 22 4636.