I don't know if someone figured out it before, I just found a theory about Chinjao from Tumblr . It makes sense to me . Ivankov once said there was a prisoner , who possesses "digging" ability, created lv5.5 in Impel Down and the chapter currently reveals the epithet of Chinjao is "Drill", so maybe Chinjao used to be a prisoner being arrested in ID and then he escaped from it thanks to Luffy's struggle . He is also the person whom Ivankov mentioned . I mean epithet "Drill" seems to be associate with "digging" alility . What do you guys think of this theory ?
mm.. the digging "ability", i think the "ability" here is a 能力 (Nouryoku), the ability for Devil Fruit User, it will be make a sense if Chinjao is prisoner and a DFU,