I see! Have you solved all four questions in the Investigations screen?
The 'Culprit' question gives you a VERY big hint. After that, all you need to do is write down that person's First Name.
I suppose I'll try and try again. Perhaps it's a bug but I'll get back to you on that. Thanks.
Spoilers???
Edit: when tapping on Leandro's profile it pops up a warning screen but I just ignore it and it just works. Sometimes it doesn't. I still haven't gotten past that culprit question. It won't let me use Cato or any other named character. It's definitely not mentioned in the history logs since I've been going back and forth for 4 hours now at the time of this edit.