“. . . I’ll bet he killed a man.” She narrowed her eyes and shivered. Lucille shivered. We all turned and looked for Gatsby. It was testimony to the romantic speculation he inspired that there were whispers about him from those who had found little that it was necessary to whisper about in this world.
(F. Scott Fitzgerald, The Great Gatsby)
The first ‘that’ seems to take a role adding information about ‘speculation.’ But I’m wondering for what the second that-clause is placed. Would you let me know?