The Las Vegas hotel suite where vials of ricin were found Thursday also contained guns and literature about anarchy with information on the deadly toxin, police said Friday.
Nevertheless, Las Vegas police continued to downplay the significance of the ricin discovery, saying they had ruled out terrorism as a motive.
"I want to assure everybody that the Las Vegas Valley is safe," Las Vegas police Capt. Joseph Lombardo said. "We don't currently have any terrorist threat at this time or possibility of contamination (due) to ricin."
The Metropolitan Police Department reported one person has been injured by the biological agent. That man has been in critical condition at Spring Valley Hospital Medical Center for more than two weeks.
Police said the man is 57 years old and was staying in the suite at the Extended Stay America on Valley View Boulevard near Flamingo Road where the ricin was found.
Police have not identified the man, but a Homeland Security internal document obtained by the Review-Journal states that he is Roger Von Bergendorff.
The man placed an emergency call from the suite on Feb. 14, saying he was in respiratory distress and asking to be transported to a hospital, police said.
"He's unable to speak with us right now," said Deputy Chief Kathy Suey, who leads the Police Department's Homeland Security Division.
His medical condition, however, was consistent with exposure to the poisonous substance, authorities said.
If a person exposed to ricin doesn't die within three to five days, the victim usually recovers, according to the Centers for Disease Control and Prevention.
Seven other people, including three police officers and three employees at the long-term stay hotel, also were hospitalized as a precaution. No one other than Von Bergendorff had exhibited signs of ricin exposure.
Before Thursday's discovery of the deadly poison, hotel management and Las Vegas police had visited the suite twice without detecting it.
On Feb. 22, eight days after Von Bergendorff was hospitalized, one of the man's "relations" called hotel management to alert them to two cats and one dog that were in the suite, Lombardo said.
Management contacted the Humane Society to take care of the animals, and the cats were taken in and are in good health. A veterinarian with the society determined the dog was in ill health because of lack of food and water and the animal was destroyed, Lombardo said.
On Tuesday, management at the hotel began eviction procedures and called Las Vegas police after discovering four firearms in the suite, the Homeland Security memo states.
Police then found an anarchist textbook that was "tabbed" to a section on ricin, Lombardo said.
That discovery prompted police investigators to test the room for the deadly substance. The test was negative.
On Thursday, a man who "claimed to be a relative" was in the suite and discovered several vials of ricin in a bag, along with castor beans from which the substance is derived, Suey said.
Police have not identified the man, whom they said was 53 years old. But the Homeland Security document identified him as Thomas Tholen.
Authorities said Tholen took the vials of ricin to the manager's office. It was not clear whether Tholen knew what the vials contained.
Tholen and three other people who were inside the manager's office were taken to Desert Springs Hospital as a precaution.
Police said Tholen stayed at the Excalibur on Wednesday night. Friday evening investigators found the room was not tainted from ricin, Lombardo said.
Police believe that all of the ricin related to the incident has been contained.
Las Vegas police spokesman Bill Cassell said Von Bergendorff "is not considered a criminal suspect."
Lombardo said: "I don't want to make any conclusions with the anarchist-type textbook. It doesn't make you a terrorist because you have this type textbook. It doesn't make you a terrorist if you possess firearms."
Police said Von Bergendorff had a misdemeanor arrest several years ago but would release no other details until the ricin investigation is completed.
Suey said the suite was registered to the man, but she did not know how long he had stayed in the suite before his hospitalization.
According to the CDC, ricin can be made from waste left over from processing castor beans and can be used in cancer treatment.
"It would take a deliberate act to make ricin and use it to poison people," the CDC's Web site states. "Accidental exposure to ricin is highly unlikely."
As little as 500 micrograms of ricin, about the size of a pin head, could be enough to kill an adult.
Suey said police do not know whether the former occupant of the hotel suite manufactured or possessed the substance.
"Might he be a victim?" a reporter asked.
"That's possible," she said.
Suey said people could have any number of reasons for wanting to make ricin.
"It could be experimental just to see if they can," she said.
The last time Las Vegas police dealt with ricin was in 2003, when a 60-year-old man died after injecting himself with the poison.
Suey said the immediate concern of police after the ricin was found on Thursday was the public's health and safety.
"For the last 12 hours, our efforts have been on the containment and cleanup of the area," she said.
With that accomplished, Suey said, police were moving ahead with their investigation.
Naomi Jones, a spokeswoman at Spring Valley Hospital, said in a prepared statement Friday that all of the medical center's patients, visitors and employees are safe.
"The patient who has been exposed is not contagious to anyone else, as ricin has to be injected, ingested or inhaled," Jones said in the statement. "We are following the universal blood-borne pathogen protocols and cooperating with investigators at this time."
Las Vegas police notified hospital officials about the investigation involving the patient on Wednesday, according to the statement.
A statement released Friday by Desert Springs Hospital states that four people were taken to the facility Thursday evening for possible exposure to ricin "and are being tested and observed and will be discharged from the hospital once they are cleared by a physician per CDC protocols."
"While we cannot confirm whether the patients have been exposed to ricin, there is no risk of exposure to our patients, visitors and employees," according to the statement.
A statement from the Nevada Office of the Military states that 19 soldiers and airmen from the Nevada National Guard's 92nd Civil Support Team assisted Las Vegas police in the ricin investigation Thursday night. The team also assisted the Clark County Fire Department's hazardous materials team in the decontamination of the scene.