A private search firm says that it believes the remains of a missing 33-year-old mother of four were found Saturday in Pine County near the site she was last seen two months ago.

Lead agencies involved in the case, sheriff's offices in Pine County and Burnett County, Wis., have not officially announced that the remains are believed to be Ashley Miller Carlson, who is from Grantsburg, Wis.

Pine County Sheriff Jeffrey Nelson said in an email Sunday that "we are waiting for positive identification and will release information as we are able," adding that he is "not going to publicly speculate."

Carlson was last seen Sept. 23 in Lena Lake, a small community in the Mille Lacs Band of Ojibwe reservation about 25 mile east of Hinckley. Grantsburg is about 30 miles south of Lena Lake.

In a statement released Nov. 12 from Pine and Burnett counties, the agencies said Carlson's rental car was located Sept. 24 partially submerged in Grace Lake, a few miles north of Lake Lena.

Carlson's belongings were in the vehicle and the agencies said they didn't believe she had a cellphone when she disappeared. Over the course of the investigation, agencies said "exhaustive searches of the area surrounding her home and where her vehicle was recovered have been completed including aircraft, drones, sonar and divers used in the lake, and foot searches..." that utilized human remains detection and K9s.

"We have collectively conducted dozens of interviews, 32 search warrants, over 15 ground searches, at least seven drone searches and two searches of Grace Lake," according to the statement from lead agencies, which are being assisted by the Minnesota Bureau of Criminal Apprehension, Wisconsin Department of Justice and Federal Bureau of Investigation.

Applied Professional Services (APS), a Duluth-based search firm retained by Carlson's family in late October, released a statement Saturday stating that volunteers and the family located remains in a wooded area off of Graces Lake Road, several miles away from where Carlson's rental car was found.

"This is a sad day our family hoped would not come, and there are still many questions that need answers, but the important thing is we now have Ashley," said Krista Miller Struck, Carlson's mother, in the APS statement. "Our family received incredible support from the community these past many weeks, and we thank them, the Christian Aid Ministries volunteer search and rescue team, the many involved law enforcement agencies and Applied Professional Services for helping locate Ashley."

Carlson's family offered a $20,000 reward for information in the case. On Nov. 19, they hosted a spaghetti dinner and silent auction at the high school in Frederic, Wis., to fund search efforts.

Struck shared on Facebook after the fundraiser that she was "humbled by all of you for your generosity and outpouring of help that is being given to us in this time of need."

"Words can't describe how grateful I am. We will bring Ashley home."