Assuming for a moment that his "suicide" was akin to Arkancide, his death sent a warning to others in his profession and to the WH.
I keep thinking of Chuck Schumer telling Trump, "Let me tell you, you take on the intelligence community, they have six ways from Sunday of getting back at you."
There is an option to why Burgess committed suicide that is not fun to even consider. He worked with child protection so had access to vulnerable children. As has been stated we don’t know anything about any suicide notes, or not. Any journal? contents are not public either.
The weekend of shooting a “Pizza” box may be a clue especially when he basically said “it’s over,” my interpretation of the shots fired and statement about it not getting up again.
Shooting his phone might have been his way of deleting some bad news about his and some possible cohorts being arrested as traffickers or some such nastiness. Then the ultimate escape of killing himself, because the “pizzagate” issue wouldn’t go away.
This is all Speculation and I am so sorry if this is not who that young man was. However, in this day and age one never knows.