On Tuesday, the police located her auto parked on a street in Kingsford, south of the city centre.
Dr Reddy was attending a dental conference in St Leonards over the weekend, last speaking to her family at around 11:00am on Sunday. She spent Sunday in a hotel on Market Street in the CBD with ex-boyfriend, Harshwardhan Narde, 34, of Tamworth, a dentist who is believed to have accompanied her to the conference.
But in a shocking twist, Narde was found dead on Monday night, the day after Dr Reddy was reported missing, having been involved in a head on collision with a truck near Tamworth in what police believe was a deliberate accident.
The ABC understands the man who died was the key suspect in Dr Reddy's murder.
Less than 24 hours later police made the gruesome discovery of Dr Reddy's remains.
The police said they spoke to Narde, aged in his thirties, as part of the missing persons investigation, before his death.
Reddy told her family members she would have a late breakfast in the central business district before returning home.
Police had been searching for the western Sydney woman since her family reported her missing on Sunday. She then left the restaurant and walked south through the city towards Market Street.
Her family didn't know if she attended the parade, where she stayed on Saturday night, where she was on Sunday morning, or what happened to her auto.More news: Henderson: Derby draw disappointing, but we'll stay positive
Preethi was last seen on a CCTV footage where she was spotted at a McDonald's joint waiting for her order.
Before her body was found, a Facebook Group called "Help find Preethi Reddy" had been set up by the family to assist the investigation.
Preethi severed off her romantic relationship with Narde who, it seemed, could not handle the break-up.
"We will stay in touch with detectives as they work it all out", she said in the statement.
"I told them I might notice the auto before".
Surveillance video showed her leaving a McDonald's in Sydney, apparently alone, around 2:15 a.m., 7 News Australia reported.
"At this stage we know they met up in Sydney and now we're looking at all the movements between these two", the officer was quoted as saying.
Numerous patients of Reddy posted messages of condolences for her family on the surgery's Facebook page.
"Prior to this unthinkable event, she had been the happiest I'd ever seen her - she was living her best life", she added.