Really? With no crime commited, no physical evidence, just a bunch of heresy, you think he should be indicted and charged with obstruction? I'm beginning to think you didn't retire willingly.
As for your other question, every single politician in history is a liar, the media chooses to manipulate weak minded people like you into focusing on the negative instead of the positive.
how do you obstruct an investigation if someone else would take it over ?
Take note that people like Agnostic and others who have bought into this nonsense don't walk through each example and talk about them specifically. It's like the people who cited the number of indictments and convictions whenever someone called the Russian investigation a witch hunt, without going through each indictment and conviction, because to do so would show how they were completely irrelevant to Trump being a Manchurian Candidate.
Similarly, you don't really hear people talking about things like Trump firing Comey obstructed the Mueller investigation. Why? Aside from the fact it's friggin stupid, there is this:
(a) Trump received a memo from the Deputy AG that recommended Comey's firing.
(b) The IG said Comey was insubordinate.
(c) The POTUS had the Constitutional authority to fire Comey.
(d) Firing Comey did absolutely nothing to prevent Muller from obtaining all of the funding he requested, getting all of the subpoenas he wanted, all of the pen registers, convening a grand jury, and interviewing hundreds of witnesses.
(e) The investigation involved an alleged crime that never happened and was invented by paid opposition research.
Now if after all that you think Trump obstructed the Mueller investigation by firing Comey you have to be either not too bright, a partisan, or suffering from Trump Derangement Syndrome.
We could go through this analysis with each one of those instances of "obstruction," but good luck finding people who will do that.