|Out of universe information|
Like others, he scoffed at Daniel's theories about the Pyramids not being built by the Fourth dynasty. When Dr. David Jordan began work on the Stewart expedition, Rayner read the carbon dating analysis that indicated they were ten thousand years old, and realized that Daniel was right. Wanting to take credit for himself, he stole the Osiris key and went to the temple it was found in.
Daniel, fearing that Rayner had been taken as a host by Osiris, followed. Upon arriving at the temple, Rayner discovered a Kara kesh and a Goa'uld interactive panel. However, Osiris, having taken Sarah as a host, arrived and seriously injured Rayner. Daniel, Major Samantha Carter, and Dr. Janet Fraiser were able to find and rescue him. Jackson commented that they'd have to come up with a good story to tell him. (SG1: "The Curse")