http://fox4kc.com/2011/11/11/exclusive-irwin-family-attorney-john-picerno-talks-to-fox-4s-john-holt/
From Part 1 (bolding by me):
Q: She's not been charged, he's not been charged. The perception out there is: Why lawyer up? Why do you need a lawyer if you haven't been charged and are supposedly cooperating?
JP: Sure. I have this discussion all the time with my father, and with other people. It's a common question, and I think it's a good question. Generally speaking, someone who is going to be interrogated by the police should have a lawyer to give them advice on what their rights are, when they can refuse to answer questions and when they should answer questions. In this case, JI and DB subjected themselves to 5 different interviews/interrogations. Two without attorneys,
where they agreed to waive their Miranda rights, or at least Debbie did, and speak to LE on their own, the first time was 8 hours for JI and 11 hours for DB, they did so. And then they went back a second time, and they did so again without a lawyer. It wasn't until the third time that a family member who is also a law student suggested to them "hey, next time you talk to the police, it would be a good idea to have a lawyer go with you."