Chainsaws like that cannot be handled by a random 16 boy, unless he is the son of Hulk or Thor. Perhaps the kid texted to a friend "we cut the treeeeee" or similar.. I would be VERY surprised to finally see proven that a 16yo did this.

Side note: I have used a chainsaw numerous times in my late teens cutting down branches for a fireplace. I could never manage to cut the tree trunk pieces, even on a chopped down tree. Branches (20cm diameter or less) were easy peasy. But a 60? 70cm diameter? Nah...