The former Duke of York remains under police investigation following his arrest at his home on the Sandringham Estate in February on suspicion of misconduct in public office.
Stephen Parkinson, the Director of Public Prosecutions, has said the police investigation into Mr Mountbatten-Windsor will look at a “pattern of conduct” over a number of years.
He said he would not be surprised if the “complex” case took more than a year to conclude.
Last month, Thames Valley Police said its investigation would also examine allegations of sexual misconduct linked to his association with Jeffrey Epstein, the convicted paedophile.
Speaking on Thursday, Mr Parkinson said: “The way you look at these cases, you look at a pattern of conduct over a period of years. It’s going to involve vast quantities of data.”
He said that while some of that information was already in the public domain there would be “data beyond that” on laptops and phones which would need to be analysed as it may lead to “further strands of inquiry”.
“I really don’t think that anyone should expect an early resolution to the investigation. I wouldn’t be at all surprised if it took over a year not because of any lack of urgency, but because of the complexity, and also the international dimension is an extra factor,” Mr Parkinson added.