As opposed to your instant analysis? For one he is there and has analysed the evidence. Second he is trained in what he is doing and has experience with both suicides and murders.
Why should not the boss question an employees work? If a boss doesn't question, he's not going to get good results from the employee.
Besides, 'you get what you inspect'. You wouldn't buy a car just on the printed brochure and a salesman's word would you?
How much more serious and important is it to know what we are getting from those we elect and appoint to office. In this country it's our right to know and question.
BTW, I have this nice used car......... trust me.