Possible Clues:

• K's creator was uttering a cheque
• "The Metamorphosis" author
• "Amerika" author (see letters 3, 6, 7, 9 and 10)
• Novelist with two protagonists named simply K. and Josef K
• Novelist whose works were banned in his native land from 1968-'89
• His novella ''The Metamorphosis'' was published in 1915
• He said 'You are free and that is why you are lost'
• He wrote 'I have the true feeling of myself only when I am unbearably unhappy'