Frandi's body, along with that of Dagmar Pytlickova, also known as Dasha, was found on Sunday morning in trees near Waimate.
Police have said it is likely the 31-year-old tourist was abducted on Saturday while hitch-hiking towards Timaru.
Detective Inspector Greg Williams told a media conference yesterday police believed "the encounter with Frandi could have been somewhere between Omarama and Kurow".
It was likely Miss Pytlickova had been abducted and driven to an isolated area.
Police believed he had walked Miss Pytlickova to a wooded area 3km from where his BMW was discovered yesterday by police in Kaiwarua Rd.
It was believed Frandi had attempted to have sex with her and a struggle had followed.
The last sighting of Frandi had been at 12.30pm in Waimate, Det Insp Williams said.
Police are not seeking anyone else in relation to the crime, but want to speak to motorists who gave Miss Pytlickova a lift on Saturday.
Assistant Commissioner Malcolm Burgess told TV3's Campbell Live last night police had been investigating a new allegation against Frandi.
There was an agreement between the police informant and investigating officers to keep the detail of the new allegation "under wraps until an appropriate time", Mr Burgess said.
"Unfortunately, Mr Frandi became aware of it on Saturday."
An off-duty officer in Timaru was contacted on Saturday by someone who knew Frandi, and was concerned what he might do.
The officer quickly contacted Waimate police, who spoke to the person who knew Frandi.
"We went to find Mr Frandi and he had left his address and he never returned.
"As soon as they [Waimate police] knew that these concerns existed they acted, and I'm confident that they acted promptly and effectively."
He was confident the homicide inquiry would cover the police reaction to the information received on Saturday.
If those details needed to be more closely examined, there could be an internal inquiry.
Det Insp Williams confirmed Frandi was known to police and was jailed for three and a-half years in 2000 for abducting a 19-year-old woman for sex.
"What I would say is that what has occurred in this situation seems very similar to what occurred in 2000."
Frandi was also convicted and fined for common assault in 2005, and for cultivating cannabis and minor traffic offending in 2006.
Det Insp Williams said Frandi was also under investigation for allegations of child molestation after police received several complaints.
Det Insp Williams said it was likely Miss Pytlickova was picked up by more than one motorist before encountering Frandi.
"It is also likely that Dasha went to a cafe or takeaway during her journey between Cromwell and Kurow."
She was carrying a 60-litre blue/grey backpack.
Police needed to piece together Miss Pytlickova and Frandi's movements on Saturday afternoon and establish how they came into contact.
Causes of death would be determined by an autopsy in Christchurch.
The area where Frandi's car was found had been cordoned off and a detailed forensic examination of the vehicle would be carried out.
The police investigation was launched on Sunday after riders found the bodies in a forestry block near Waimate.
Waimate Mayor John Coles said the community was struggling to come to terms with the tragedy.
"For me personally, this is something no mayor ever wants to happen where you've got deaths in the community, particularly in this way. It's pretty hard to deal with and being a small community we all know each other, even though I didn't know the man personally.
"There are still a lot of questions that I have got in my head and I guess they will be trying to sort those issue out.
"I just put my faith in the police that they will get to a greater understanding of what happened here."
