New figures showing that just 3pc of rape reports are being prosecuted in the county have been labelled 'a disgrace' by Norfolk's police chief.
Four years ago a quarter of reports of rape in Norfolk resulted in a file being passed to the CPS for prosecution.
This year the figure had fallen to 3pc - just one in every 27 cases, according to EDP analysis of Home Office data.
At the same time the number of rape reports the force is dealing with has tripled.
Chief Constable Simon Bailey said there is "no straightforward answer" to the problem, but said it is a "disgrace".
He cited delays in bringing cases to court and investigative problems in non-recent cases.
"There is a real challenge at this moment in time in terms of maintaining and securing the confidence of victims because of the amount of time it is taking to investigate these matters," he said.
"There is issues around CPS availability to deal with the review of the files and the test they are applying.
"There is no doubt we have seen a reduction in files being transferred to the CPS and that is something I am looking at through my public protection work.
"We have got victims disengaging, and it is not unusual to wait one or two years for a case to come to trial.
"We are reviewing lots of reports of non-recent sexual assaults and rape which have really tough investigative opportunities.
"These are being looked at by the criminal justice board and the National Police Chiefs Council lead is doing a bespoke piece of work to look at that reason."
The revelations come as the Victim's Commissioner Dame Vera Baird said rape prosecutions had "fallen off a cliff" and called for an end to "digital strip search".
Rape complainants will have their phones examined to aid disclosure.
"Complainants must be treated with dignity, given specialist support and, where necessary, legal advice on issues such as disclosure of personal data," said Dame Vera.
"Police and criminal justice agencies must ensure that complainants are kept informed about case progress and use bail to give protection whilst minimising the current long delays between report and trial.
Mr Bailey added: "The whole of the country has seen a dramatic reduction in the number of cases being transferred."
He added he was "concerned" about the trend.
"It is very complex and is being looked at at the highest levels of the police service," he said.
"Our performance is marginally better than at national level, but it is a disgrace what is currently happening.
"We have some real challenges around this."
Nationally the number of rapes being prosecuted has fallen to 1.7pc.
Norfolk's Police and Crime Commissioner Lorne Green called the figures "unsettling".
'Ridiculous' court delays
Rape victims have previously slammed "ridiculous" delays in bringing their cases to court.
Michelle Brown, 26, waived her right of anonymity to speak in January of this year of how her recovery was delayed by the slow wheels of justice.
She was the victim of a horrific sex attack in which she was tied to her bed and "subjected the most terrible, extreme sexual abuse".
Gary Nathan, 52, of Pottergate, Norwich, admitted false imprisonment, three counts of causing a person to engage in sexual activity without consent, two sexual assaults and a robbery.
Nathan was ordered to serve a minimum of 10 years in prison before he can be considered for parole when he was sentenced in November last year.
But that was more than 500 days after the offences occurred in May 2017, and Miss Brown said her life was put on hold due to the "ridiculous" delays.
"I found the court system significantly lacking and incompetent," she said. "I was advised that the reasons for delays included either waiting for reports from probation or reports that were unacceptable. And the delays lasted months.
"I find this disgusting that I, as a victim of a serious offence, was the one constantly let down and caused further distress because of the flaws in our system and incompetent staff unable to complete their work effectively and on time."
And the CPS accepted delays had been "unacceptably long" after Anthony Holloway evaded justice for two and a half years after an attack on a woman with dementia.
Holloway, 54, of Peregrine Road, was initially charged in December 2015 with rape, but after months of court delays the case did not get to trial until September 2017.
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