Oops! Dropped cards onto hand
I don't see any way this odd scenario should result in DEC (short of Alfred picking up the entire pile and saying “OK, this is now my hand”… and that's not happening in real life).
For that matter, this probably isn't an infraction at all - although Looking at Extra Cards is a likely outcome, soon after dropping those cards. (It's not a certainty!)
How I would probably resolve this:
* ask both players “how many cards were in hand” - hopefully we the same answer from both; if not, we're still OK; this just helps us with the rest, it isn't critical
* ask Alfred (away from the table) to tell me which cards were in his hand
* compare his memory to the cards on the bottom of the pile
* restore his hand based on which of the bottom cards match his memory
Could he lie and hit that 1-in-X chance of getting it right? Sure… and the San Andreas fault could “invalidate” your next event. Let's not let either of those unlikely possibilities influence policy, m'kay?
(almost) Worst case: Alfred can only remember 3 or 4 of the 5 cards that were in his hand, or he thinks there were 5 but the opponent only recalls 4. If Alfred insists it was 5 and can accurately name the 5 cards on the bottom of the pile, we can easily believe that he's correct.
Even worse case: Alfred managed to mix / shuffle some or all of those cards from his hand into the bottom of the cards that were dropped onto his hand. In that case, he's still likely to be able to name most of the cards that will now be among the bottom 8-10 of that pile; your investigation and decision re: his honesty are more important, but it's still within reason to believe him, and restore the contents of his hand.
And at the end, if there's no indication that either Alfred or his opponent could have seen any cards, there's no infraction - just a friendly “please be more careful”, and a time extension.
d:^D