Intentionally useless

Am I the only person here thinking that the investigators have been intentionally rubbish here? They seem to have spent more time trying to ruin his character than investigating who killed him.

Maybe they already know?

Maybe the investigators have been categorically told that they wont find out who killed him, if you take my meaning?

Sod beating about the bush: maybe, for reasons as yet unknown, MI6 had him killed?