Without the key, will be a miracle.
I have used ciphers in past for various activities, but I also know the key.If he had memorised the key and not written down, will be shear luck.
On the other hand guy may have been a nut( Barney Fife)
It will be more difficult not knowing info about the man...note that there are three numerals on bottom of p1. Do they, or a relative-addition combo, mean anything? It seems to have an unencrypted possessive apostrophe-S combo.