Several vials of ricin powder were found in his room two weeks later after a friend went there to remove Bergendorff's belongings.
Investigators were speaking with Bergendorff for the first time Friday, said Special Agent David Staretz, an FBI spokesman. Neither he nor Las Vegas police would provide more information.
Authorities hope Bergendorff can provide information about the discovery of the deadly powder, along with castor beans from which it is derived, at an extended stay motel where he had been living several blocks from the Las Vegas Strip.
Officials have said they've found no contamination anywhere, and no link to terrorism in the discovery of the exotic toxin, which can be lethal in amounts the size of the head of a pin. Ricin has no antidote and is legal only for cancer research.
In court documents made public this week, police call ricin a "biological weapon" and say four "anarchists cookbooks" marked at sections describing how to manufacture ricin were found in Bergendorff's room.
Friends and family members describe Bergendorff as an unemployed and unmarried graphic artist, a recovering alcoholic who loved his dog and cats and struggled to pay his bills while living in Huntington Beach, Calif., Reno, the San Diego area and a pickup truck camper near Salt Lake City. He moved in recent months to an extended stay motel several blocks off the Las Vegas Strip.
A younger brother, Erich Bergendorff of Escondido, Calif., said hospital officials told him Wednesday that his brother was awake and had been told that his beloved dog, Angel, was euthanized after the Humane Society found her starving and without water in his motel room.
"It was my impression that they were able to communicate with him and he had talked enough to ask a few things," said.
Authorities suspect Bergendorff was exposed to ricin, and experts have said his symptoms appeared consistent with ricin exposure. The poison breaks down in the body within days, however, making it difficult to trace.
