Latin to English Art/Literary Poetry & Literature Valerius Maximus

Greetings,

They say you can’t give too much context so...:)

Antius Restio, proscriptus a triumviris, cum omnes domesticos circa rapinam et praedam occupatos videret, quam maxime poterat dissimulata fuga se penatibus suis intempesta nocte subduxit. cuius furtivum egressum servos ab eo vinculorum poena coercitus inexpiabilique litterarum nota per summam oris contumeliam inustus curiosis speculatus oculis ac vestigia huc atque illuc errantia benivolo studio subsecutus lateri voluntarius comes adrepsit.

I’m really not sure how to translate this faithfully: could “nota” be a past passive participle? Whatever it is, is it ablative?

If “nota” agrees with “inexpiabili”, how can a mark or brand be unforgivable? The sense would seem to demand inverted commas in modern usage: branded with the letters “unforgivable/irredeemable” but that doesn’t square with the text.

Best wishes,

Simon