Try these with 9 letters - assuming the letters offered can only be used once upt o the maximum times they are offered.
archaisms, archaists, arythmias, caryatids, catharsis, <Aa target='_blank' href=http://www.a2zwordfinder.com/anagram.html>d ramatics, dyscrasia.
Hope somebody can give a longer word for you detective.
ATB.