And so eventually somewhere in this MtGox account thread they stated that they do, but don't share this information publicly.
They said they were filing a report with the police and could not publicly discuss the information they had while the matter was being investigated. They did not say that they knew who the hacker was. They said they knew where the transactions went. That information may allow the hacker to be traced but it doesn't mean that MtGox is aware of their identity.