WASHINGTON, March 4 (UPI) -- Ricin has been a byword for terrorism in the mass media since Colin Powell used it to link Iraq-based terrorists to groups plotting attacks in Europe as part of the U.S. case for invasion in 2003. But the ricin in that incident turned out to be no more real than Saddam Hussein's weapons of mass destruction, and experts say that the toxin is so difficult to purify it is unlikely to ever be used successfully in a terror attack.

Samples of the substance found in a Las Vegas motel room last week after its occupant was hospitalized with breathing difficulties will be analyzed by the federal Centers for Disease Control and Prevention in Atlanta and the FBI's Hazardous Materials Response Unit, officials told United Press International Monday.

Two CDC specialists were already in Las Vegas at the request of state and local authorities, the agency's spokesman Von Roebuck told UPI. He said they were working to help ascertain what had sickened Von Bergendorff' title='Roger Von Bergendorff' class='tpstyle'>Roger Von Bergendorff, a resident at the Extended Stay America motel who was hospitalized Feb. 14 and remains in critical condition.

Experts say that with no conclusive analysis of either the substance or the patient it is hard to tell what might have been found in Bergendorff's room, and some accuse local officials -- and the news media -- of getting out ahead of the story.

"There are field tests, but the lab testing will eliminate the possibility of a false positive," FBI spokesman Richard Kolko acknowledged.