During this period, the professors of all houses urged the students not to wander around alone, to avoid lingering in the castle at night, and constantly escorted students to and from classes. Even so, another student was petrified.
The petrified student was a Muggle-born named Justin, and petrified alongside him was a ghost—Nearly Headless Nick.
They were petrified in the corridor outside the library. Harry happened to be at the scene yet again, and was spotted by Professor McGonagall and some Hufflepuff students.
Chapter 108