LAS VEGAS — Vials found in the motel room of a man hospitalized in critical condition tested positive for the deadly toxin ricin, authorities said today.

There was no indication of any link to terrorist activity, the Las Vegas police Deputy Chief, Kathy Suey, said at a press conference.

The man was admitted to Spring Valley Hospital in Las Vegas in critical condition on February 14, a hospital spokeswoman, Naomi Jones, said. Chief Suey said he had made an emergency call for help because of breathing problems. His name was not made public.

The investigation of the apparent ricin didn’t begin until yesterday, police said, after someone Chief Suey identified as “a friend or relative” went to the sick man’s hotel room to retrieve his belongings and found “several” vials of a powder and brought it to the motel manager. Police were ultimately called to the Extended Stay America Motel several blocks west of the Las Vegas Strip.

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, Chief Suey said. All were released overnight.

Ricin is made from processing castor beans and can be extremely lethal. As little as 500 micrograms, or about the size of the head of a pin, can kill a human, according to the Centers for Disease Control and Prevention at Atlanta.

“During our investigation we did find that there was a subject who had been a previous occupant of that hotel room who is currently hospitalized in critical condition here locally as a possible result of exposure to ricin,” Chief Suey said.

Two preliminary tests, one by police and one by the Nevada National Guard, concluded that the substance was ricin. A third test from a local lab confirmed the results, Chief Suey 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,” she said. “We don’t even know that it was him that was in possession of the ricin.”

Police said the sick man, believed to be in his 40s or 50s, is not considered to be a criminal suspect. Chief Suey said he was unconscious, and police had not been able to interview him.

Chief Suey would not say how many vials were found or how much ricin they contained. Officials said the vials were in a plastic bag, and castor beans also were found in the room.

Police said they spent 12 hours containing and cleaning up the site.

“My understanding is cleanup has been done. There should not be a threat to anybody at this time,” the chief health officer of the Southern Nevada Health District, Dr. Lawrence Sands, said.

Ms. Jones, the hospital spokeswoman, said no one else at the hospital is at risk of exposure.

“The patient who has been exposed is not contagious to anyone else, as ricin has to be injected, ingested, or inhaled. We are following the universal blood-borne pathogen protocols and cooperating with investigators at this time,” Ms. Jones said.

The motel manager had begun an eviction because the sick man hadn’t paid his bill, and the man who found the vial had gone to the room to retrieve his belongings. Chief Suey said he claimed to be a relative of the sick man.

Chief Suey said there were several pets in the room when officers arrived. A dog was found dead but the animal had gone at least a week without food or water, Chief Suey said, and she did not attribute the death to ricin.