Three police officers face misconduct hearings over the handling of abuse allegations against Lostprophets' singer Ian Watkins.
The hearings come after Watkins was jailed for 35 years in 2013 for serious child sexual offences.
Watkins, 36, was arrested in 2012 and accused of attempting to rape an 11-month old child and encouraging a fan to abuse her own child.
However, the Independent Police Complaints Commission (IPCC) said South Wales Police was given information about Watkins back in 2008.
An IPCC investigator has recommended that a detective sergeant has a case to answer for gross misconduct.
It is alleged the officer did not take sufficient action to progress enquiries, and contributed to allegations from a main witness being treated as unfounded.
The IPCC investigator also found that two detective constables have a case to answer for misconduct.
It is alleged they did not undertake all reasonable and practicable lines of enquiry.
Watchdog officials added that they have also recommended a further case to answer for gross misconduct against the detective sergeant's "lack of action" about reports that a 15-year-old girl was raped.
The allegations concerning Watkins and the teenager did not feature in his prosecution.
However, a court was told about Watkins's fantasies with underage girls as well as a disturbing encounter with a teenage fan.
Watkins had originally denied any wrongdoing - claiming he had been "framed" by jealous groupies.
However, he changed his plea just moments before his trial was due to start and admitted 13 child sex offences.
Cardiff Crown Court judge Mr Justice Royce handed the shamed rocker a 29-year prison term - with a further six years on licence.
Watkins later launched an appeal against the length of his sentence, but it was dismissed by a panel of judges.