On: The Truth About Tonkin (2008)

[Stratoscope]

It sounds like the phrase did confuse you.

"I can't help but be sceptical..." simply means "I am skeptical..."

Try that substitution in your example and it should be more clear:

> It’s like finding a notorious serial killer standing over a body holding a knife who says, “a ghost did it.” “I am skeptical about the ghost....”