Days later, after Lin is safe and sound and staying with Katara because spirits what the hell is that girl doing, playing around with Azula?!, Toph truly becomes aware of the problem. Her officers are breaking the law. Her officers know she's aware of them breaking the law. And they're still getting away with it.
But, the more pressing concern is that Azula won't talk. She refuses to eat, sitting in the corner, holding something to her chest. She won't say who committed the crime—won't say anything.
And Lin is right in the middle.