What made Rafferty believe that the visitors at Mr. Alsop’s place were Aliens?

Rafferty believed that the visitors at Mr. Alsop's house were not normal people when he realized that he was looking at them slyly. This was an indicator that he was suspicious of them and didn't want to be caught staring at them or analyzing them. He realized that these guests were not ordinary people. He had also witnessed a plane without wings, a spaceship, and thought that he could have a story only if he cracked open the source location of the visitors.

i needs a girlfriends

we need to see the document to answer the question