I'm very surprised with this answer.
First, I think your title is a bit misleading. From what I understand, it is your computer who has been hacked, but I can't understand Kraken's answer. They should be able to give your complete logins and transactions history. No need to be an official. There's something really wrong here.
I don't know if my computer was hacked. But at least Kraken should help me to understand what has happened.
Another email from them:
As per our previous reply, unfortunately we will not be able to provide any further information about this case until we are contacted by a verified law enforcement official.
We would advise you to file a police report and ask the law enforcement official responsible for this investigation to contact us by submitting a Compliance and Legal web form - https://support.kraken.com/hc/en-us/requests/new?ticket_form_id=648008