I've a suspicion here that you might be asking in the wrong place. (Sorry!). This is a UK-based site and the usual way in this country to end up as a prosecutor is to start off by getting a law degree following a fulltime course at university (or alternatively getting a good honours degree in another subject and then studying for a Graduate Diploma in Law). There's then a further year of study on the Bar Professional Training Course and a year of practical training. That qualifies someone to practice as a Barrister. They might then be able to get employment with the Crown Prosecution Service but in order to be the lead prosecutor in major cases they would need to seek appointment as a Queen's Counsel. The application process takes between three and five years, with candidates typically having had around a decade of experience of working as a barrister before even being able to apply.
There is ultra-fierce competition to become a barrister and it would be hard to do so via any paralegal route. (It would theoretically be possible for someone to train as a legal executive, then to study further to become a solicitor and then to seek to become a barrister but such a path would be difficult to follow and would take many years. There would then still an average of 13 more years before becoming a QC, if that were even possible).
Relevant links (for the UK):
https://www.prospects.ac.uk/job-profiles/barrister
and
https://www.thelawyerportal.com/free-guides/how-to-become-a-barrister/what-is-a-queens-counsel-barrister-how-to-become-one/
However I suspect that you're not in the UK. Things might be very different in your home country and it would be best to seek information on a website based there. Sorry!