From Akif Pirinçci's story.

I keep thinking about "Felidae" characters design. For example, came to conclusion that Claudandus - in spite of his regenerate abilities - needs scars from most hard Preterius's experiments. BUT! Scars will be visible only when his fur stands up - in moments of intense worry or anger. And this scars are much thin than fresh wounds in the central portrait.

Symbolic image in lower left corner, as I've think, is part of work of someone from cult (most likely Father Joker himself, lol). It's also intended to confuse watcher a bit, cause it outwardly resembles other suspects - Bluebeard and F.J. by nature of wounds or facial features.
Ah, YES, one more thing: an attentive watcher may notice that the largest scars on Claudandus's face are the initials of Professor Preterius. o_O

(I don't give up hope to improve my skill and finally illustrate this book in the next couple of years)