The body of 25-year-old kindergarten teacher Simone Strobel was found concealed under palm fronds at a sportsground in Lismore, in the NSW northern rivers region, in February 2005.
A second inquest opened in Sydney on Monday to examine a big swathe of evidence that has emerged since a 2007 hearing was unable to find any person directly responsible for her death.
Counsel assisting Philip Strickland SC said the evidence to be examined included lies told by Ms Strobel's boyfriend at the time, Tobias Moran, about their relationship.
Mr Moran, who attended the inquest, was charged with Ms Strobel's murder in 2022 before prosecutors opted not to proceed and the charges were withdrawn.
Ms Strobel spent the two weeks leading up to her death travelling the east coast of Australia with Mr Moran, then known as Tobias Suckfuell, his sister Katrin Suckfuell and a fourth person, Jens Martin.
All three people initially lied to police about whether Mr Moran and Ms Strobel had been arguing, how intoxicated they were on the night she went missing and whether they had consumed illicit drugs, Mr Strickland said.
Whether those lies indicated consciousness of guilt would be a key question for the inquest, Mr Strickland said.
Some of Simone Strobel's diary entries in the days before her death were read to the inquest. (HANDOUT/NSW POLICE)
On the night of the disappearance, the group was seen drinking heavily in a nearby hotel and continued to consume alcohol and smoke cannabis after returning to the campground.
The group told police Ms Strobel left the campsite after becoming annoyed with Mr Moran as he and his sister argued about what was described as "family matters".
"All three of them said Simone left the caravan park and they never saw her again," Mr Strickland said.
If Mr Moran was involved in murdering Ms Strobel, it was "the most plausible route, if not the only plausible route" that Ms Suckfuell and Mr Martin were also involved, Mr Strickland said.
"If Tobias killed Simone and did it alone, he had a very narrow window in which to leave the caravan park, find Simone, kill her, take off her clothes, dispose of her body," he said.
"He would have had to have done so whilst he knew that his friend and his sister were searching in the same area for Simone."
Simone Strobel's group told police she left the campsite after becoming annoyed with her boyfriend. (Jason O'BRIEN/AAP PHOTOS)
Diary entries by Ms Strobel in the days before her death, and partly read to the inquest, recorded issues in her relationship with Mr Moran and the mood of the group.
"Today began just as s*** as yesterday ended," Ms Strobel wrote on February 11, the day before she was reported missing.
In another entry from about the same time, she wrote she was getting "the baddest vibration" since arriving in Australia with Mr Moran.
Mr Moran later admitted having lied about the extent of issues the pair was having, but said his intention was for Ms Strobel's disappearance to be taken seriously by police, the inquest was told.
Ms Strobel's brother and sister, Alexander and Christina Strobel, travelled from Germany to represent the family at the inquest.
Alexander Strobel, with sister Christina, said they hoped to find the truth about Simone's death (Bianca De Marchi/AAP PHOTOS)
"Today we heard in court ... that Tobias Moran lied consistently to police and our family about the circumstances of my sister's murder," Mr Strobel told media.
"We are very hopeful that during the course of this inquest we will find out why so many lies were told and what is the truth about my sister's death."
The week-long hearing will examine physical evidence, Simone's cause of death and various other persons of interest identified as being potentially involved.
Mr Strickland said the area where Ms Strobel's body was found is near a known "crime hotspot" in Lismore and that on the night she disappeared several locals where known to have been drinking in the area.
"There is no doubt that on the night of Simone's disappearance …. men with serious criminal backgrounds were lurking nearby," he said.
