Mafia 37. Haven of Evil.

July 20, 1988

88
As everyone knows, this is half of "14/88".
Also, on July 20th, let's check the wiki.
Wikipedia

The culmination of the conspiracy was the failed assassination attempt on Hitler's life on July 20, 1944.

Let's look at Reinhard's guesses.

Remember what I said about the eight and its perfect symmetry? Divide the last eight in the date of birth in half, and what do you get? Four! So, it's 1984!

But you need to divide both eights, and you get 1944!!!
And everyone knows that the Third Reich had a very large supply of chemical weapons. Chemical weapons - Thorium.