Christopher Phillips is back in Nova Scotia after being arrested on a Canada-wide warrant in Ottawa.​

Today, Nova Scotia RCMP charged the biochemical weapons specialist with possession of a weapon for a dangerous purpose related to the chemical osmium tetroxide, according to a police news release. He was also charged with uttering threats to police to cause bodily harm or death.

The offences are alleged to have happened between Dec. 26 and Jan. 21.

The 42-year-old Cole Harbour man was transported to Nova Scotia from Ottawa on an RCMP plane.

Police and hazardous materials teams are using this red tent as their base to investigate the Nova Scotia cottage linked to Christopher Phillips, who was arrested Wednesday on a Canada-wide issued by Nova Scotia RCMP. (Molly Segal/CBC)

At a Thursday afternoon press conference, RCMP Cpl. Greg Church said the case is very serious.

"The potential that exists currently with the information that we have is rather enormous,"​ he said.

Church would not speculate on how or why the chemical was in Phillips's possession.

Nova Scotia RCMP searched two properties linked to Phillips this week and said there is no site contamination at the Cole Harbour property where a suspicious package containing hazardous chemicals was found Tuesday in the garage of the home. Homes around the house were subject to an evacuation order.

RCMP and a hazardous materials unit are at a cottage in Grand Desert, N.S., trying to determine what kind of chemicals are at the location. Officials evacuated five nearby homes on Wednesday

Church would not confirm whether chemicals listed in court documents were found in the Grand Desert cottage.

Phillips was arrested by Ottawa police on suspicion of carrying two dangerous chemicals from Nova Scotia to Ottawa. Police had been tipped off by the man's wife that he was on his way to the capital. But a search by police did not turn up any chemicals in his hotel room or vehicle.

RCMP said the evacuation order is still in place in Grand Desert, but residents can now travel through the area on Old Dyke Road under police direction.

Dave Croft, who lives near the cottage, said Phillips struck him as odd.

"He said that he was using it for storage," he said. "It seemed odd because most Americans that come up here come up here for the view, and to use cottages for what cottages are used for, right? And they’re really nice, but this guy wasn't so nice."

Earlier this week, RCMP identified Phillips as a biochemical weapons specialist, who was formerly in the military. It was also noted that he has possible mental-health issues and is considered "anti-police," sources confirmed to CBC News.

The chemicals police thought Phillips might have been transporting to Ottawa included:

Osmium, a precious metal.

Osmium tetroxide, a highly poisonous and volatile chemical that can penetrate skin easily and should not be handled without a fume hood.

Ottawa police evacuated the Chimo Hotel at 1199 Joseph Cyr St. on Tuesday night and closed off the surrounding roads as a precaution when they learned Phillips was staying there. After talking with him for several hours, Phillips surrendered to police without incident Wednesday morning.