The Police Ombudsman has launched an inquiry into how RUC police officers investigated the killing of a Portadown teenager 12 years ago.
It is understood that there are more than ten RUC investigations, including several murder probes, in which the RUC officers failed to examine vital evidence, follow up crucial leads or pass on intelligence to investigating officers.
It is believed that further criticisms from the ombudsman could force the British government to instigate a formal inquiry into the RUC. This follows O'Loan's damning assessment of the RUC's murder probe into the killing of prominent GAA man Sean Brown in 1997.
Brown was abducted and shot dead while locking up Bellaghy Gaelic sports club house in Derry.
O'Loan concluded in her report on the Brown case that RUC officers had failed to pass on evidence for forensic examination, that they failed to interview a key witness, that Special Branch had held back vital intelligence from investigating officers, and that files relating to the murder inquiry went missing just weeks after her office began examining the case.
O'Loan described the disappearance of the files as ``sinister''. Her report on the Brown investigation described it as ``appalling and unprofessional'' and said the ombudsman's office had uncovered ``serious and unexplained errors''.
Sixteen-year-old Alice McLoughlin from Portadown, County Armagh, died after accepting a lift in an off-duty officer's car in July 1991.
She died after being shot the head by a single bullet, allegedly fired from a RUC officer's gun.
Concerns were raised about how the original probe was conducted by RUC officers at the time. The McLoughlin family have always maintained that their daughter could not have been responsible for taking her own life.
A lobby group pushing for a fresh inquiry into the teenager's death - Justice for Alice - asked the Police Ombudsman Nuala O'Loan to re-examine the investigation.
Barry Bradbury, spokesman for the group, welcomed the new inquiry. He said: ``Over the past 13 years the McLoughlin family has had to suffer and live with untruths told by the security forces regarding their daughter's death.''
A spokesman for Mrs O'Loan confirmed that her team has started examining how the shooting was investigated at the time.
``We have begun an investigation into the circumstances surrounding the death of Alice McLoughlin,'' the spokesman said.
``There has been a lot of speculation about Alice's death and there have been allegations of police misconduct. We will be hoping to get to the bottom of these allegations of police misconduct.''
The police ombudsman's office issued a fresh appeal for information on the case.