Police believe Anthony was abducted and tied to a chair on a rural property, before he was killed by a truck on the M1.
A couple from Cudgera Creek – Mark Frost, 46, and Lauren Grainger, 38 – have since been charged with taking or detaining a person with intent to obtain advantage.
Homicide detectives are trying to piece together what happened in the five hours before the teacher was killed.
Police are investigating if Anthony was abducted from his Fortitude Valley home in Brisbane before being driven in his own BMW down to Cudgera Creek.
“We believe he was detained against his will at that premises prior to his death … these circumstances are very troubling,” acting Superintendent Brendon Cullen told reporters.
“He was restrained within that place – we do believe he may have suffered injuries while in there,” acting Supt Cullen said.
The teacher, who worked at St Peters Lutheran College Springfield, and was described by the school in a statement as "popular and well regarded" was last seen on security camera when he flew into Brisbane from Sydney.
"We want to further about what happened and the circumstances around Mr Scott’s death," said a police spokesperson last week.
Anthony had only just returned to the country from a trip in Peru, landing in Sydney earlier last week, then at Brisbane Domestic Airport on Sunday afternoon.
"We have recovered his vehicle, which was located abandoned near the scene on the M1 about 2am on Monday morning.
"We want to speak with anyone on the NSW Far North Coast or across the border in Queensland who may have had dealings with or had spoken with him since Sunday 9 February.
"We’re also wanting to speak with anyone who may have seen his vehicle on Sunday afternoon– a silver BMW with NSW registration ANL 72Y.
"Piecing together his movements in the 24-hours prior to his death is crucial and I urge anyone who may have any information to contact Crime Stoppers."