How is "author" defined for fixing git on reboot and distribution?

Question

I mixed up a colleague branch that had 2 commits, and crushed the second commit in the first. He retained the original author (i.e. not me).

Suppose I want to fix one line of code, so I cancel the hunk and make a new commit.

At that moment, I returned to where I started, with two commits that I want to crush together, and I want to keep the original author. However, in the earlier case, both fixations had the same author. In this latter case, commits crushed have different authors. Which author is git assigned a new rebased / squashed commit?