Scores of volunteers showed up at Faith Lutheran Church in Great Falls to assist in the search for Amy Harding-Permann.
Harding, a 34-year old nurse in Great Falls, was last seen leaving her residence at 343 Flood Road on foot at about 8:30 p.m. on Sunday, Jan. 26.
Cascade County Sheriff Jesse Slaughter provided an explanation of the area and guidelines and safety concerns for searchers; initial estimates indicate that more than 150 volunteers showed up.
He said that additional search volunteers are not needed at this point, because they don't want to have to explain all of the guidelines to every new person that arrives.
However, people are welcome to drop off bottled water and/or refreshments at the church for the searchers.
Sheriff Slaughter said on Monday that Harding-Permann got into an argument with her boyfriend John VanGilder at the residence.
She then allegedly assaulted him before leaving the house and headed in the direction of the Missouri River, which is very close to the house.
VanGilder told police she was not dressed for the weather as she was only wearing a long sleeve shirt and yoga pants.
Sheriff Slaughter said that search crews were called out quickly because Harding was not dressed for the weather; temperatures at the time were in the 30s, with wind-chills below freezing.
"At the point that our initial search did not find her, due to the weather conditions, her not being dressed appropriately and due to the environment and conditions we were in, she was a missing person,” he explained.
On Tuesday, Sheriff Slaughter declined to release details of any possible criminal investigation, and stressed that at this point, it remains a missing person investigation.
However, MTN News has learned that the house has been secured by law enforcement since the investigation began.
Searchers and detectives from the Sheriff's Office, the Great Falls Police Department, Malmstrom Air Force Base, and rural fire departments have been searching on the ground, in the river, and in the air.
Search dogs are also being used.