Which phrase in this excerpt from act 1 of Henrik Ibsen's A Doll's House suggests that Krogstad is prone to engage in crime and may, in fact, be a criminal?
RANK: Certainly. However wretched I may feel, I want to PROLONG THE AGONY as long as possible. All my patients are like that. And so are those who are morally diseased; one of them, and a bad case too, is at
this very moment with Helmer—

MRS. LINDE (sadly): Ah!

NORA: Whom do you mean?

RANK: A lawyer of the name of Krogstad, a fellow you don't know at all. He suffers from a diseased moral character, Mrs. Helmer; but even he began talking of its being highly important that he should live.

NORA: Did he? What did he want to speak to Torvald about?

RANK: I have no idea; I only heard that it was something about the Bank.

NORA: I didn't know this—what's his name—Krogstad had anything to do with the Bank.

RANK: Yes, he has some sort of app