Detectives suspect some of Tiahleigh Palmer's classmates know what happened on the day she disappeared, but aren't speaking up because they fear they'll get in trouble.
It's been two weeks since the 12-year-old was last seen alive, when her carer dropped her at Marsden State High School at Logan, south of Brisbane. Her body was found on the banks of a Gold Coast river six days later.
Detective Superintendent Dave Hutchinson on Friday renewed calls for public assistance, saying police were sorting through 327 tip-offs made to Crime Stoppers.
Supt Hutchinson said police were also working through conflicting accounts given by students of what happened.
"(We) have a little bit of a concern that some of the students know a little bit more than what they're telling us and they're a little bit concerned that what they tell us might get them in trouble for some minor reason," he said.
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"We're telling them they're not going to be in any trouble just because they know that this was going to occur."
Supt Hutchinson said students' fears probably come from suggestions Tiahleigh had planned to wag school the day she went missing.
He said that plan made police think she had organised to meet up with someone.
"The chances of her on the very day that she decides to wag it that she's picked up by a random person is statistically low, but we don't discount that," Supt Hutchinson said.
He renewed calls for anyone with dash cameras on their vehicles who drove past Marsden State High School on October 30 to contact police.
Detectives have set up a marquee outside the school, hoping it will jog the memory of someone who may be able to provide a vital clue to determine what happened to Tiahleigh.
Police are waiting for forensic tests on Tiahleigh's body after a post-mortem examination was unable to determine a cause of death.
A group of fishermen found her decomposing body, without her school uniform or the distinctive purple backpack she was last seen with, on the banks of the Pimpama River on November 5.
