The sentence suggests that the evidence was abundant or sufficient, which is necessary for solving a crime.
"Copious" and "Ample" are both suitable to describe evidence in this context as they suggest that the evidence was abundant or sufficient.
Arun’s present age in years is 40% of Barun’s. In another few years, Arun’s age will be half of Barun’s. By what percentage will Barun’s age increase during this period?