GOLDEN, Colo. -- Some Jefferson County sheriff's employees may be given lie detector tests during an internal investigation into how more than 60 secret Columbine High School crime scene photos were leaked.

The Rocky Mountain News reported Tuesday that it and some families of the 1999 shootings at Columbine had obtained the photos but did not say how.

"If it's necessary to use the polygraph to resolve this matter, I'll take the first one, and the sheriff certainly will do so as well," Jefferson County Undersheriff John Dunaway said.

He and Sheriff John Stone (pictured, left) were the only two officials with the authority to release any of the 10,000 or so crime scene photos. Dunaway said neither had leaked the photos.

"I would resign in a heartbeat over an issue like that," Dunaway said.

The department regards the photos as stolen.

"This may prove to be a criminal investigation," sheriff's spokeswoman Jacki Tallman said.

The News said the photos show the bodies of killers Dylan Klebold and Eric Harris, their victims, scenes from the school's library and cafeteria, and bombs the killers made. The News has not published the photos.

Dunaway said two of the photos faxed to him by the newspaper appeared to be authentic.

Tallman said many of the 34 law enforcement agencies involved in the Columbine investigation had access to crime scene photos.

Security has been increased in the sheriff's office, and employees may be required to work in pairs when handling the photos.

Family members of some Columbine victims said Tuesday that Stone should resign. They said the Sheriff's Department had promised the photos would never be made public.

Two years ago, Columbine families were upset when Stone and Dunaway allowed a Time magazine reporter to watch videos taped by Klebold and Harris before the families saw them. Families were also angered when the sheriff and undersheriff also posed with the weapons used by the killers for the front page of the magazine.