A Simple Tier 1 Spell is Easy
The forest wasn't that dense, which allowed people to walk through it without problems. Arthur went there with his gaze focused on the ground, looking for footprints or any sign of strange activity.
It did not rain in the last few days, so the tracks should be there, unless someone intentionally covered it up.
"Could the werewolf return to his human form and erase the clues? If so, how did he escape the school perimeter with no one noticing it?
Something smelled fishy, and as Arthur was feeling hopeless about finding something, he did.
First, he saw a tree branch broke in half. Anyone or anything could have done that, but right in front of it there was a bush, and behind that bush, a footprint.
Arthur crouched and tried his best to analyze that footprint. He had some knowledge about magical beasts, but not to the extent of knowing exactly what it was at first glance.