LOS ANGELES, Mar. 1 (Xinhua) -- Investigators were still trying to figure out a mystery about how a rare, deadly poison was brought to a motel in Las Vegas, about 260 miles (416 kilometers) northeast of Los Angeles, authorities said on Saturday.

    Adding to the mystery, police said firearms and an "anarchist type textbook" were found in the same room where the ricin was discovered two days later.

    The 57-year-old man who stayed in the room remained unconscious in a hospital so investigators could not get any information to piece together what had happened, police said.

    Police found the firearms and books on Tuesday after a manager at the Extended Stay America motel called police upon discovering weapons, Las Vegas police Capt. Joseph Lombardohe said, without elaborating.

    After authorities seized the book and weapons, tests for ricin were conducted but came back negative, Lombardo said.

    The deadly substance was found in several vials of powder in a plastic bag in the room on Thursday.

    But there was no evidence to link the incident with terrorist activity and no indication of any spread of the substance beyond the place where it was found, police said.

    "There is no information to lead us to believe that this is the result of any terrorist activity or related to any possible terrorist activity," police Deputy Chief Kathy Suey said earlier.

    A friend or relative of the sick man found the vials after going to the motel, several blocks west of the Las Vegas Strip, to retrieve his belongings, according to Suey.

    But it remained unknown why and how the ricin was taken to the room.

    Tests by homeland security officers, the Nevada National Guard and a laboratory in Las Vegas came back positive for ricin, Suey said. A cleanup of the motel has been completed, she added.

    Seven people, including the man who found the ricin, the manager, two other motel employees and three police officers, were decontaminated at the scene and taken to hospitals for examination, but none have shown any signs of being affected by ricin, Suey said.

    Ricin is highly poisonous and a pinprick of ricin is enough to kill.