Unfortunately I came to recently see the truth in that myself - prosecutions are NOT in any way a search for the truth. In fact, if a prosecutor comes across something truthful that contradicts his prosecution he will lie & obstruct to cover it up. Never mistake a prosecution for a search for the truth.
you just discovered that prosecuters will hide exculable evidence? you haven't been in court have you? its all about batting avg. The more wins-- the faster the promotion.