The professional thief, surprisingly enough, is the ideal recruit if you want somebody good at breaking in and stealing things. Unfortunately, this is a hidden job, and professional thieves show up masquerading as other character types when you run across them in site mode. To find one, the most straightforward option is to recruit a bunch of prisoners and hope there's a professional thief among them. The fastest way to get prisoners is to break into the prison on the outskirts of town, but you'll probably have to shoot your way out. Note you'll get some worthless small-time characters too if you're freeing prisoners, and you'll rack up heat pretty fast.
If you'd rather play it safe, you can search for people who seem slightly "out of place" in the homeless shelter or crack houses -- folks like painters, sculptors, socialites, things like that. Those people might be professional thieves, and you should be able to find out their true profession by asking them on dates or getting them into a recruiting session, then viewing their character sheet. Unless you have a very strong recruiter, I would recommend dating over talking about the issues, as professional thieves, even if liberal, are not generally socially conscious enough to be as receptive to normal recruiting as the hippies at the vegan co-op are. Naturally that means someone with good seduction though, so it might be worth recruiting a prostitute first and having them conduct the search.