Bought 4 of these for less than $10 each

I bought four of these original sketches for $30. I have spoken to people and have been told they are highly collectable. They are supposedly french courtroom drawings. They are signed by the author but I can't make out the name it looks like J Hoff and I can't make out the remainder. I dont want to sell them just curious as to information about specifcally the name of the author and what they may possibly be worth.