SAN QUENTIN, Calif. —  Prison guards searched the death row cell of Polly Klaas' killer after learning he may have corresponded with the suspect in the decade-old slaying of JonBenet Ramsey, authorities said Friday.

Guards at San Quentin State Prison searched Richard Allen Davis' cell Thursday, but found no letters from John Mark Karr.

Davis, 52, was sentenced to death for the 1993 kidnapping and murder of 12-year-old Polly Klaas. The girl was from Petaluma, where suspect John Mark Karr lived from 2000 to 2001, when Karr was charged with misdemeanor possession of child pornography.

Lt. Eric Messick said officials decided to search Davis' cell after learning that Karr had told detectives in 2001 that he had a letter from Davis and was researching a book on him.

"Our reasoning was that if there was evidence of them having this relationship, then it might shed some light on things — it wasn't a far reach," he said. "But I don't think we've found anything so far suggesting there was a nexus between Davis, Karr and JonBenet Ramsey. Obviously Richard Allen Davis was in prison at that time."

Calls to Davis' lawyers Friday were not immediately returned.

Karr, 41, was awaiting deportation from Thailand on Friday. He told Thai authorities that he sexually assaulted JonBenet, the child beauty queen who was found beaten and strangled in the basement of her family's Colorado home on Dec. 26, 1996. Karr said he killed the 6-year-old girl accidentally.

Lt. Gen. Suwat Tumrongsiskul of the Thai immigration police initially quoted Karr as saying he had also drugged JonBenet. On Friday, Tumrongsiskul backed off that statement, explaining that Karr described the encounter with JonBenet Ramsey as "a blur."