LAS VEGAS — A man who stayed in a Las Vegas hotel room where ricin was discovered on Thursday has been hospitalized in critical condition since Feb. 14 with symptoms consistent with exposure to the deadly toxin, Las Vegas police said Friday.

The man’s identity, age and hometown were being withheld on Friday as investigators tried to determine why ricin, as well as castor beans from which is it derived, were found in a room at an Extended Stay America hotel one mile west of the Las Vegas Strip.

Deputy Chief Kathleen Suey said the man had been staying in the room where the ricin was found for an unknown length of time and was leasing the room when the substance was discovered. A man, said to be a relative or friend of the sick man, had gone into the room to retrieve the patient’s belongings when he found the vials of white powder and showed it to the hotel’s manager, Deputy Chief Suey said.

Police were called by the hotel. The man had been hospitalized on Feb. 14 with respiratory distress but did not indicate to doctors that he may have been exposed to ricin, so the health district and police were not notified of the prospect, she said.

An evacuation ensued and seven people were taken to local hospitals for treatment, though they were released when they showed no signs of exposure, Deputy Chief Suey said. The hotel was reopened early Friday after public health officials determined they had found and removed all the ricin.

The patient has not yet been questioned and is believed to be unconscious, she said.

F.B.I. national spokesman Richard Kolko said the incident did not appear to be related to terrorism “based on the information gathered so far.” [Emphasis added]