Transcript for Chris Christie Defends Himself on Radio Show
I got an e-mail from Harper, we have school today, right? Yes. Chris Christie, his top aide fired for her role in bridgegate is refusing to cooperate with investigators taking the fifth as Christie faces questions for the first time in weeks on a radio call-in show. ABC's Reena ninan has the story. Reporter: If you thought he was down for the count -- I've been very clear about this. Before these lanes were closed I knew nothing about it. Reporter: -- Chris Christie came back swinging. I didn't plan it. I didn't authorize it. I didn't approve it. I knew nothing about it. Reporter: His first interview since a former transportation official and former ally David wildstein alleged Christie lied and evidence exists Christie knew about the George Washington bridge lane closure while it was going on. And this was Christie's response. Did I have any knowledge of it beforehand and the answer is still the same. It's unee quickly no. Reporter: But admitted he's still in the dark about some parts. I still don't know whether there was a traffic study that morphed -- You still don't know at this point whether there was a traffic study. What I'm saying, Eric, did it start as a traffic study that morphed into political shenanigans or did it start as political shenanigans that became a traffic study. Reporter: Cornered with the news breaking overnight his former deputy chief of staff Bridget Anne Kelly is taking the fifth. Refusing to turn over subpoenaed documents. When she didn't tell me the truth and I fired her. I would hope they would share any information they had that would let me get to the bottom of it but on the other hand, they have constitutional rights like everybody else. Reporter: Just what toll has this had on his family? My wife and my kids, they know me and they know there's nothing to be worried about. Because I told them the same thing that I just told all the people who are listening tonight, is that I had nothing to do with this. And now New Jersey lawmakers and the U.S. Justice department are investigating. Both have subpoenaed Christie's office for documents which Christie says they'll provide.
This transcript has been automatically generated and may not be 100% accurate.