HALIFAX -- A former U.S. resident was flown to Halifax on Thursday to face charges of uttering threats and possessing a weapon for a dangerous purpose as the RCMP continued to investigate the discovery of hazardous chemicals in two residences.

Christopher Burton Phillips, 42, was brought back by the RCMP to Nova Scotia from Ottawa, where he was arrested a day earlier at a hotel that had to be evacuated.

Police allege in a sworn information at provincial court that Phillips threatened a police officer and possessed osmium tetroxide, a highly toxic chemical.

The document alleges the offences took place between Boxing Day and Wednesday in Cole Harbour, a suburb of Halifax.

An investigation into the discovery of hazardous chemicals at two Halifax-area residences -- one a home assessed to be worth about $515,000 in Cole Harbour and a second a tiny coastal cottage with peeling red paint -- prompted separate evacuations earlier this week.

RCMP Cpl. Greg Church said two chemists from Health Canada are helping with the investigation. Church said an evacuation that was ordered around the cottage in Grand Desert, N.S., about 35 kilometres east of downtown Halifax, is expected to remain in effect overnight.

"We have here of course a situation with several unknowns," Church said Thursday. "We do have two very serious criminal charges that have been laid against the individual."

He said there is no reason to believe that the areas that have been evacuated are contaminated. He declined to comment on whether the osmium tetroxide listed in the sworn information was found at the residences.

John Holmes, a professor emeritus of chemistry at the University of Ottawa, said when in fine powder form, osmium tetroxide is hazardous and can cause death by damaging the lungs when inhaled.

"One would handle it with great care," he said. "If it's in a screw top jar it's safe to handle. If it's a sealed container it's not dangerous.

"If you inhaled it as a powder it would be lethal."

He said the substance can be purchased from large chemical companies but is intended for use in laboratories by chemists.

"Having it at home would ... be called a bit foolish."

Ottawa police arrested Phillips at the Chimo Hotel on Wednesday and linked the arrest to the discovery of the chemicals in Halifax. Police said they did not find hazardous materials in the Ottawa hotel.

The RCMP said it issued a Canada-wide warrant after a "large quantity" of chemicals were found inside two homes in Cole Harbour and Grand Desert.

Church declined to say why the alleged offences span for almost a month, adding that he had "no idea" what the suspect's motivation may have been with the chemicals.

American court documents say Phillips was an ophthalmologist prior to moving to Nova Scotia, where his wife lives and works.

Among those documents is an April 2008 report from a Texas psychiatric hospital that says he was diagnosed that year with a mood disorder, an addiction to painkillers, an alcohol problem and narcissistic tendencies.

Phillips suffered an undisclosed "traumatic injury" to his feet while serving in the U.S. navy, which granted him a medical discharge, according to court documents he filed as part of a lawsuit against a former colleague in Washington state.

U.S. navy Lt. Joseph Keiley said in an email the navy has confirmed that a man with the same name and birthdate as Phillips served in the navy, but further details on his service were unavailable.

The company that employs Phillips's wife as a medical director issued a statement Thursday saying it is providing support to Dr. Gosia Phillips while she deals with "this unfortunate situation." MedSleep, a sleep medicine clinic, said it will not comment further.

Phillips was previously married to Shannon Miller, a gold medal gymnast with the U.S. Olympic team.

With files from The Canadian Press's Steve Rennie in Ottawa.