Is it right for the justice system to pursue criminal charges several decades after the crime is said to have occurred?

Yes, I think that it is still right to pursue someone's crime even though that it has been committed a few decades ago. One must always pay the price for one's wrongdoing no matter how long has it been. Imagine you are the victim. Your son has been kidnapped by a kidnapper syndicate and they had amputated his limbs and position him somewhere in the world to act as a beggar to beg for a living. Finally after 15 years, you see your son again in Thailand and also managed to find the syndicate. Of course, you will be hating the syndicate for what they have done to your child and the separation between a parent and a child. You will also want them to be punished for their crime-doings as wells as the misery they have brought to other kids and parents. Now, after this small"simulation, you will realise that crime-doers will always have to be punished all else the world will be unfair and they will never learn. Time should never be part of the consideration as justice needs to be served.