Key evidence that's gone missing in the child pornography case against John Mark Karr could set the one-time JonBenet Ramsey murder suspect free from criminal charges for a second time.

Karr's lawyers argued Wednesday that the five misdemeanor charges against their client should be dropped amid revelations that the Sonoma County Sheriff's Department lost the computer that allegedly held the pornographic images, as well as copies of its contents.

Three hard drives, a laptop computer, diskettes and a zip drive were seized from Karr's home when he was arrested in 2001, but he fled before his trial.

Sheriff's Detective John Eubanks, however, testified that he recently found more child porn among 1,600 pornographic images on about 100 diskettes, CDs and a removable disk drive taken from Karr in 2001. He has not been charged in connection with those images.

Sonoma County Superior Court Judge Cerena Wong interrupted Eubanks' testimony, calling his analysis of the other evidence irrelevant.

"That computer which contained those five images is missing," Wong said.

Sheriff's property room chief Helga Ritter described hours of repeated and systematic searches that failed to turn up the missing computer.

"We checked every computer that we had," she testified. "This is the first time this has ever happened."

With the copies also missing, all that remains is reports from the 2001 investigation about what was contained on the computer.

Defense lawyer Gayle Gutekunst argued that she now has no way to properly defend Karr nor would prosecutors be able to make a case against him because "the crime scene is gone."

Karr rejected a plea deal and remains jailed on $200,000 bail. He chose not to attend Wednesday's hearing.

The 41-year-old former schoolteacher was arrested in Thailand last month after suggesting he killed JonBenet, a 6-year-old beauty queen, in her Boulder, Colo., home in 1996. He was returned to the U.S., but the Ramsey case quickly collapsed after DNA failed to connect him to the crime.

Earlier, Wong said she sealed police records in the Karr case partly because Chief Deputy District Attorney Joann Risse had said they were still examining the computer. She criticized Risse for misleading her and said she would reconsider unsealing the search and arrest warrants when the hearing continues Friday.

Ritter said she told the lead investigator as early as Aug. 18 that the computer was missing. The prosecutor admitted she knew about it since Aug. 30.

Gutekunst, who wasn't notified until Sept. 21, said she believes "what may have started out as sloppiness," may now rise to "bad faith" on the part of the prosecutor and worthy of possible sanctions.