Three years since a new law aimed at domestic abusers who control their partners' behaviour came into force, two of every three reports end with no action.
Hundreds of reports of coercive and controlling behaviour are now made each year in Norfolk, since the introduction of the Serious Crime Act 2015.
But just one in ten results in a charge, and two thirds end with no further action.
Norfolk's domestic abuse charity Leeway has said they hope 'more action is taken' to protect victims, including a new domestic abuse commissioner to make the response to all domestic abuse 'consistent'.
Since it became an offence in late 2015, almost 500 reports of coercive and controlling behaviour have been made in Norfolk.
More than half of those were made in 2018, as the number doubles each year.
But two of every three reports end in no further action. It could be due to evidential difficulties or the victim withdrawing support for the prosecution.
Temp Det Sgt Andy Coller, head of safeguarding at Norfolk Police, said losing the support of the victim in a case creates difficulty.
'We can look to follow an evidence-led prosecution and try to build a case without their support,' he said.
'It would be even harder to solve than a case of assault, where you might have some witnesses or officers turning up and seeing fresh injuries.
'Because of the nature of the offending you are going to want to show how it has operated over a period of time and the different tactics employed.
'To prove the case you need to have the victim on board and willing to provide that evidence. Because people are so fearful and have been controlled they may be more worried and less willing to give evidence.'
Further safeguards can include alarms, referrals to Leeway or disclosures of a partner's offending history under Clare's Law.
T/DS Coller added the new law has helped prosecute offenders who might otherwise have escaped justice.
'It has brought into play some elements of behaviour which are really damaging but weren't captured by previous legislation,' he said. 'This offending is pervasive and totally changes lives.
'Previously if an offender was clever and did not physically harm their victim it would be really difficult to get a charge in place.
'In the past people might have viewed these cases as morally wrong but not actually a criminal offence. Now more people are becoming aware of it.'
Charities feel more needs to be done to protect victims, with hopes riding on a new Domestic Abuse Bill, drafted in January.
It was shaped in part by the tragic story of Kerri McAuley, beaten to death by her controlling ex-boyfriend Joe Storey in January 2017.
The domestic homicide report into her death revealed the lengths he went to exert control over her, including 2,500 calls and 19,000 texts in seven months.
When she tried to leave him, he claimed he had a brain tumour.
Mandy Proctor, chief executive of Leeway, said it was 'positive' to see coercive and controlling behaviour included in the statutory definition of domestic abuse.
She said: 'Gathering evidence is also key and it is important that as much evidence is gathered by the police in the 'golden hour' as possible, including communications via text, social media and voicemails. This helps to strengthen a case, increasing the chances of securing a conviction.
'Coercive and controlling behaviours can be hard to spot with the naked eye as the abuse is not always physical, where you may see bruises or broken bones. It could be that a perpetrator controls a victim through threats of violence if they do not do as they say, which cannot be visibly seen.
'This means it can be harder to obtain evidence or may take longer to investigate, which could result in a victim dropping the case – they could have been coerced to do this by the perpetrator or by the perpetrators family or friends.'
She added she hopes the number of arrests will increase as more people become aware of what sort of behaviour is now criminal.
'The impact that coercive control has on those that experience it is massive with victims often isolated and living in fear of their partner,' she said. 'It is important that reports of these types of behaviours are taken seriously and investigated accordingly.
'There are still many people that do not recognise the signs of coercive and controlling behaviours though, so continuing to raise awareness is important, particularly of the pattern of controlling behaviours and examples of this.'
Anyone experiencing domestic abuse can call Leeway on 0300 561 0077, or in an emergency call Norfolk Police on 999.
Man hid tracker in car and bugged the sofa
One of the 50 people charged with coercive and controlling behaviour in Norfolk was Stephen Ross, of Salhouse.
He was jailed in May 2017 for 16 weeks after fitting a tracker in the family car and secretly recording conversations from a device in the sofa.
The 48-year-old, of Mill Road, pleaded guilty to carrying out the offence of engaging in controlling/coercive behaviour in an intimate/family relationship.
Ross also controlled the family finances, according to the prosecution.
Prosecutor Alison Cotterill said: '[The victim] became isolated from friends as a result of his behaviour.'
She added the victim changed from a 'strong and independent woman' to someone who was 'anxious, tearful and exhausted', according to friends.
Ross was also ordered to pay £800 in compensation and given a two-year restraining order.
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