Questions are being asked of education officials about how they dealt with warnings of a relationship between a teenager and her married teacher before they eloped to France.
East Sussex County Council confirmed it and school officials were "addressing and investigating concerns" that were raised about the closeness of 15-year-old Megan Stammers and Jeremy Forrest, 30.
The teenager's mother and stepfather have said they were unaware of any relationship, and Sussex Police were only made aware of it last week.
Concerns were expressed to another teacher about the contact between Megan and Forrest following a school trip to Los Angeles in February, according to reports.
A friend of Megan's said another classmate raised the issue after seeing the pair holding hands together on the return flight, and they would often hug each other, said the Daily Mail.
Some campaigners said that any suspicion of inappropriate contact at Megan's school, Bishop Bell C of E in Eastbourne - where Forrest taught maths, should have been dealt with by suspending him.
An East Sussex County Council spokesman said: "Because the investigations are ongoing we are not going to comment in detail.
"However, the school and the county council had been addressing and investigating concerns that had been raised, in line with procedure, when this happened. That investigation will continue and we will decide what action to take."
Officers believe friends might hold clues about where Megan and Forrest might be. Chief Inspector Jason Tingley said they should not feel scared of divulging information not previously disclosed.
He said: "We do know that (Megan) has spoken about perhaps going somewhere but we just need to get really into the specific detail of that."