Why did Alaska state trooper Roger Ellis lose his skepticism as he talked to Jim Gallien?

From the text:

But Gallien persisted, and the more he talked, the more Ellis’s skepticism receded. Gallien described several pieces of equipment not mentioned in the newspaper account that matched gear found with the body. And then Ellis noticed that the first cryptic entry in the hiker’s journal read, “Exit Fairbanks. Sitting Galliean. Rabbit Day.”