It is intriguing. From a primary English speaker this sounds odd (meaning it sounds as if he is admitting he would be lying if he told her he wasn't involved). Obviously it could have come out worse if he doesn't speak/understand English from birth. I could easily see this going either way. Imagine it from a strong English speaker, then imagine that answer from someone who isn't so strong. "I can not do that," could simply be frustration. I mean he had to call the cops. Anyway, we could parse this forever. I guess we'll find out for sure one day.