An independent watchdog is to investigate a police force over the collapse of a trial of four men accused of the gang rape of a woman at a leading university.
Thady Duff, Leo Mahon and Patrick Foster, all 22, and James Martin, 20, were accused of raping the woman at a summer ball at the Royal Agricultural University in Cirencester, Gloucestershire, in May 2014.
She claimed she had been subjected to violence, including strangulation, and some of it had been filmed and posted on Snapchat.
The trial had been due to begin at Gloucester Crown Court in March but, following delays due to the late disclosure of evidence and a review of the case, the prosecution offered no evidence and the four defendants were cleared.
Last week during a hearing on defence costs, Judge Jamie Tabor QC, the Recorder of Gloucester, criticised Detective Constable Ben Lewis, the lead officer.
The judge said Det Con Lewis had got too close to the complainant and did not understand his job properly, which led to "stark and very serious omissions" by the officer in failing to disclose "game-changing" evidence.
The Independent Police Complaints Commission has decided an independent investigation is "appropriate".
"The circumstances of a criminal investigation conducted by Gloucestershire Constabulary, which was unable to proceed to trial due to issues raised during legal proceedings, will be examined by the Independent Police Complaints Commission," the IPCC said in a statement.
"Issues have been raised concerning the police investigation and the disclosure of evidence in preparation for the trial.
"The matter was referred to the IPCC and we have decided an independent investigation is appropriate.
"The IPCC will carefully examine the actions of the officers involved during both the investigation and the pre-trial process."