Presumably they both care about careers and reputation.
Epsiein's family pathologist only gets paid as long as he's involved in the investigation. If he said "Yep, looks like a suicide", the family would have no further use for him. But if he discovers some conspiracy that will take an indefinite amount of time to deal with, he keeps collecting paychecks. Also, this fellow seems to thrive on fame, so even more incentive to find something juicy.
Naive.
(... and thanks to the power of conspiracy theories, he's now got a cemented reputation forever among some circles).
Not that I think there's any sort of attempts at influencing the story here...
Either: They want the truth or they want to distort the truth.
In the first case: Why don't they trust the state?
In the second: Why do they want to falsely make it to look like a murder?