"I do have the authority to impose a sentence higher or lower," U.S. District Judge Robert C. Jones said. "Do you understand?"
"Yes," Bergendorff answered in a clear and steady voice.
Bergendorff pleaded guilty to possession of a biological toxin and possession of unregistered handgun silencers. A third charge of possession of firearms without serial numbers was dropped.
Prosecutor Gregory Damm reiterated the case had no ties to terrorism.
Jones set sentencing for Nov. 3.
Bergendorff has been in federal custody since his arrest April 16, when he was released from a hospital after spending nearly two months unconscious and on kidney dialysis. Authorities suspect he poisoned himself in his room just off the Las Vegas Strip, and have said Bergendorff's symptoms were consistent with ricin exposure.
Cancer research is the only legal use for ricin, which has no antidote and can be lethal in amounts the size of the head of a pin.
Bergendorff's attorney, Paul Riddle, denied that ricin made his client sick.
"He still maintains that it wasn't the ricin," Ridrn a telephone message seeking comment.
Federal prosecutors allege Tholen, 54, knew Bergendorff made ricin in Utah before moving to Las Vegas.
