A. 10 million USD

B. 50 million USD

C. 200 million USD

D. 1.3 billion USD

Details About Most money spent on an investigation:

MIT math genius Ted Kaczynski went nuts as a young man and started living off the grid in his early 20s. He detonated sixteen bombs by mail, resulting in three fatalities and numerous injuries. This resulted in the longest-ever FBI investigation for a found criminal, spanning 17 years and costing $50 million.