In addition to being a contemporary of Socrates and of the same deme (i.e. township), Crito was also a dear friend. Socrates had a modest amount of money and entrusted Crito, who was wise in the affairs of business, to invest it for him.
He appears in Plato's Euthydemus,
Crito. In the
Crito, he is a main character, and he attempts to convince
Socrates to flee prison.