The official website has been updated with character profiles including Apollo's and the case one witness', Barashima Shingo's:

http://www.capcom.co.jp/gyakutensaiban/5/

For Apollo's profile description, here's the gist of it by Court Record:

However, it leaves his backstory in mystery, simply asking what could possibly have caused these injuries and if that coat carries any special meaning. Could he be connected to this case…?

Source: http://court-records-net.tumblr.com/post/45317662046/