Steve Baldwin, senior investigating officer for the organisation dubbed the ‘British FBI’, said the 1,400 CSE victims in the town who were identified by Professor Alexis Jay last year in her damning report on what happened in the town was a “very good estimate”.
The agency also confirmed that two ‘current or former’ Rotherham councillors are under investigation over allegations they were involved in child sexual exploitation.
The NCA investigation, given the name Operation Stovewood, began in December after the agency was asked to intervene by South Yorkshire Police.
This followed Prof Jay’s report which painted a shocking picture of hundreds of children being raped, trafficked and groomed by mainly Asian gangs in Rotherham between 1997 and 2013.
The report, which was published in August last year and was highly critical of police and local authority actions over 16 years, shocked the nation and led to a wave of high profile resignations.
Mr Baldwin said his team, made up of 32 officers split into four groups, had identified more than 3,300 lines of inquiry as part of a “massive evidence-gathering operation”. The operation is expected to expand in the coming weeks and months.
He said they had examined 47 boxes of written material, including 1,500 files, from the outreach group Risky Business, which started to identify vulnerable girls and young women on the streets of the town as early as the late 1990s.
The officer confirmed most of the potential suspects were Asian men from the Rotherham area and most of the victims were white British girls and young women.
Officer in overall command of Operation Stovewood, Trevor Pearce, said: “It is clear that some details provided will be duplicates of other details, names, nick-names or street names. Others may not prove to be offenders at all, or may be witnesses to abuse,”
NCA officials said the cost of the investigation was between £3 million and £5 million a year, and could last for another two or three years, meaning South Yorkshire Police face paying out up to £15 million by the time the process is finished.
Mr Pearce said: “I would be surprised if in two or three years time we weren’t still processing people through the criminal justice system.”
Reflecting on the abuse of young girls in Rotherham over two decades, Mr Pearce added: “For a large number of young girls I think it’s fair to say their lives have been stolen. The dreams or views that you have got when you’re 13 - that has not happened.”
He added: “I thought long and hard at the start of this about what a successful outcome would look like. Is it that there will be x-hundred people going through the criminal justice system successfully, clearly that is the normal one we use.
“There is an outcome that those victims who we have come into contact with feel they have been listened to, and they have had a better experience.
“There is a third element, which is, when is the community of Rotherham able to have confidence in the statutory agencies, that their vulnerable ones are being looked after.
“Yes, we want to see people convicted, if points two and three happen without conviction, or we can get through to a lot of these victims and they can say ‘at least we’ve had a fair hearing’, and they have been approached properly and professionally, and they can be put into the right therapeutic environment, that for me is a bit of the success criteria.
“There are people who have committed dreadful offences against young women, principally, in Rotherham. I think they need to face justice and have their day in court, and we are absolutely endeavouring to move into the suspect identification and going forwards, when it is the right time.
“What I want to see is us having successful prosecutions with the CPS, whereby we can achieve the right results in court.”
The probe is focusing on the abuse of young children and not the apparent failures by police and council officials that allowed it to happen.
But the NCA has referred the case of two South Yorkshire Police officers to the Independent Police Complaints Commission, who are looking into alleged misconduct by officers over two decades.
The IPCC is already examining more than 100 complaints against 42 named police officers, both retired and serving, in relation to the scandal - including suggestions of ‘corrupt relationships between police officers and offenders’.
Mr Baldwin, a former detective with Greater Manchester Police and the National Crime Squad, said: “The abuse that has taken place in Rotherham is horrific. We have gathered a huge amount of information which details some very disturbing events.
“Work to identify all victims of non-familial CSEA in Rotherham between 1997 and 2013 is ongoing. I would say that Alexis Jay’s estimate of 1,400 victims remains a very good assessment.
“We will prioritise action against suspects who may continue to pose any risk of harm today and those who have caused most harm in the past. We will examine all allegations of abuse and, most importantly, we will listen to victims.
“I know that there are more victims yet to be identified and for us to reach out to. Progress will be best achieved at present by tackling what we have now and demonstrating through our actions that we deserve the trust and confidence of others.”
Both officers stressed that the operation was not going to rush to make arrests. Mr Baldwin said there was evidence the men involved were sometimes operating as part of organised networks and it was important to fully understand these conspiracies before rushing to prosecute individuals.
The Operation Stovewood team includes NCA officers and some South Yorkshire Police staff, but no South Yorkshire Police officers.