Why does Dormer hesitate to sign Ellie's report?

During the course of Insomnia Ellie is given the task of investigating the death of Det. Eckhart, who is supposed to have been shot by the killer, but who we know was shot by his partner Det. Dormer. When Ellie has finished her report she hands it to Det. Dormer to sign it. Yet he rejects it and says she should double check it and make sure everything is correct (forgive me for not quoting it word-accurate):

Ellie: My report, it's finished. You only have to read and sign it. It basically explians itself all by itself. Looking forward to working with you again, we got more important things to do here than this paper work.

Dormer (retreating the pen): A man is dead Ellie, that is important. Make sure of all the facts before handing this in, your name is on this report.

But right before reading that report he went out of his way to cover his guilt in Eckhart's death and foist it on the killer (e.g. by hiding the gun and substituting the bullets). So why would he now urge Ellie to investigate further if he could just have had it filed away by simply signing her report? (And indeed she finds contradictions between his statements and the evidences after looking further.)

plot-explanation insomnia

Best Answer

Dormer is a good man at the core, though he has done bad things with good intentions. He ultimately wanted to be held accountable, even if he couldn't quite admit it to himself until the end. The insomnia was a metaphor for his guilt.

It's likely he saw a young, idealistic version of himself in Ellie, and did not want her to become corrupted.