Since Dumbledore didn't give anyone else access to an undisturbed scene, it's merely the best conclusion that anyone could draw who wasn't an actual professional investigator / smart person.
Actual professional investigators would know not to come to any conclusion without actually investigating the scene. (Whether or not they trusted Dumbledore to investigate is a different matter.)
Smart people would think:
They have already marked the Night of Godric's Hollow, as reported by Albus Dumbledore, as an anomalous and potentially important event. They have wondered why it happened, if it did happen; or if not, why Dumbledore is lying.
This is a new thread to discuss Eliezer Yudkowsky’s Harry Potter and the Methods of Rationality and anything related to it. This thread is intended for discussing chapter 116.
There is a site dedicated to the story at hpmor.com, which is now the place to go to find the authors notes and all sorts of other goodies. AdeleneDawner has kept an archive of Author’s Notes. (This goes up to the notes for chapter 76, and is now not updating. The authors notes from chapter 77 onwards are on hpmor.com.)