Three South Yorkshire police officers are being investigated for gross misconduct by the Independent Police Complaints Commission.
The trio are being investigated alongside two Bedfordshire bobbies and a South Wales officer as part of an IPCC probe into the handling of allegations against disgraced rock star Ian Watkins.
The former Lostprophets frontman was jailed for 35 years last December for a string of child sex offences, including attempting to rape a baby.
He confessed to 13 offences at Cardiff Crown Court - where he was described as a committed and determined paedophile.
A 21-year-old mother from Doncaster, who cannot be named, was sentenced to 14 years for allowing the singer to abuse her own baby.
Another mother from Bedford area was jailed for 16 years.
An IPCC spokeswoman said the South Yorkshire officers are being investigated over the handling of three reports made to the force between March and May 2012 which contained allegations against Watkins.
IPCC Commissioner Jan Williams said: “Arrangements are being made to interview the officers.”