The body of Joanne Eddison, 15, who went missing in May 1996, was discovered nine weeks later on a railway embankment 100 yards from her home in Charlton, south-east London.
Liam Tovell, 16, was later jailed for seven years after admitting manslaughter. But the prosecution claimed in court that he may "have got away with murder" because the delay in finding her body meant it was impossible to determine how she died.
The British Transport Police officers were asked to search the area where the body was found. Five officers from the Metropolitan Police and five from the BTP have received formal warnings or "advice". One BTP officer faces a disciplinary charge.