Police have given the all-clear after authorities checked an unidentified white powder a man reported finding in a Las Vegas Strip hotel room.

Authorities say a substance found Tuesday in a room at the Excalibur hotel-casino is not hazardous but have not disclosed what the substance is.

The 44-year-old called hotel workers to his room after claiming he woke up with white powder covering his bed, FOX5Vegas.com reports.

Hazardous materials teams were on the scene to investigate, and the powder's make-up had not been determined.

Clark County Fire Department spokesman Scott Allison said one theory is that laundry soap may have been left on the sheets. The man is not sick and authorities do not believe he was exposed to anything dangerous. The hotel, which features 3,991 guest rooms, was not evacuated.

Last week police recovered firearms, an "anarchist-type textbook" and castor beans, from which ricin is made, in another Las Vegas hotel where vials of the poison ricin were found. The book was tabbed at a spot containing information about ricin.

Authorities believed they had found all of the ricin recovered Thursday from the Extended Stay America motel in Las Vegas where Roger Von Bergendorff had been staying, but they wanted to also check the home in Riverton, outside Salt Lake City.

"We are taking all the precautions necessary to ensure public safety," FBI agent Timothy Fuhrman said at a news conference Sunday.

Nearby homes were evacuated as FBI agents, covered from head to toe in full hazardous-material protection suits, meticulously searched the home belonging to Von Bergendorff's cousin Thomas Tholen.

Fuhrman announced Sunday night that the search of the home and three storage units had concluded, but would not say whether the agents found anything related to the ricin scare in Las Vegas. Fuhrman did say after the daylong search that all of the Utah locations were safe.

Von Bergendorff had been staying in the motel room where the ricin was found and has been hospitalized since Feb. 14. Von Bergendorff has been unconscious, so police and the FBI have not been able to question him about the ricin found in his room.

Health officials are still trying to confirm whether Von Bergendorff's respiratory ailment stemmed from ricin exposure.

The FBI got a search warrant for Tholen's home, where Von Bergendorff once lived.

Fuhrman said it would be a long process because agents were potentially dealing with such a toxic substance. He would not say whether the FBI suspected that Von Bergendorff had manufactured or stored ricin in the home or the rented storage units.

Residents from three surrounding homes were allowed to return by Sunday afternoon.

Click here for more on this story from FOX5Vegas.com.

The Associated Press contributed to this report.