Ex-partner of missing Minnesota mom arrested in connection with her disappearance

The ex-partner of a Minnesota mother who has been missing since March under suspicious circumstances has been arrested in connection with her disappearance after her remains were found, authorities said.

Madeline Kingsbury, 26, was last seen the morning of March 31 when she and her children's father dropped their two young children off at a day care before returning to her home in Winona, according to Winona Police Chief Tom Williams. The children's father, Adam Fravel, told police he left the house in Kingsbury's van around 10 a.m., but when he returned later that day, Kingsbury was not there, Williams said.

Amid the search for Kingsbury, a Fillmore County deputy found human remains Wednesday afternoon in brush off Highway 43, north of Mabel, Minnesota, which "was located using information generated during the Madeline Kingsbury investigation," the Winona Police Department said in a social media post Wednesday night.

"Because of this, law enforcement personnel have arrested Adam Fravel on probable cause in connection to her disappearance," the department said.

Fravel, 29, is being held on a second-degree murder charge, online jail records show.

The location where the remains were found -- a wooded area off of a gravel road -- had been previously searched, but Kingsbury's body was "covered and concealed in such a manner that she was not visible," according to Williams.

"Unfortunately, while this discovery is not what we were hoping for, we are thankful to be able to bring Maddi home to her family," Williams said during a press briefing on Thursday.

Williams said he was unable to comment on her cause of death at this time.

Kingsbury's family also confirmed Thursday that she was found.

"We're relieved that Madeline has been found after months of intensive searching and grateful for the extraordinary efforts by law enforcement, other first responders and volunteers," her family said in a statement.

Following Fravel's arrest, they said they are "looking forward to getting justice for Madeline."

Fravel was arrested at a residence in Mabel without incident, authorities said. Law enforcement did not comment on the case involving Fravel amid the investigation.

Williams said investigators had "mountains" of digital evidence, including phone and computer data, that led them to the area where Kingsbury was found. The location was within several minutes of the Fravel family's property but was not owned by the family or any of their relatives, authorities said.

Early in the investigation, Williams said police believed Kingsbury's disappearance was "suspicious" and "involuntary," and that they were concerned for her safety.

There was no indication Kingsbury left home on foot or in another vehicle, and her cellphone, wallet and ID were found in the house, according to Williams.

The day she went missing, Kingsbury did not show up for work and did not respond to "numerous" calls and messages from friends and family and failed to pick up her children from day care that afternoon, which is "extremely out of character for her," police said.

Her disappearance has prompted thousands of volunteers to help in the search.

Investigators received more than 450 tips, according to Minnesota Bureau of Criminal Apprehension Special Agent Michelle Frascone.

"It's this kind of collaborative effort that brought us here today, able to bring closure to Maddi's family," Frascone said during Thursday's briefing.

In the weeks after she was reported missing, Fravel denied having anything to do with her disappearance.

"Over the course of the last 12 days, my family and I have been subject to a myriad of accusations regarding the disappearance of the mother of my children," Fravel said in a statement released by his attorney on April 14.

He said he has been cooperating with authorities and that investigators advised him not to attend press conferences or searches "due to safety concerns."

Kingsbury's family offered a $50,000 reward for information leading to her whereabouts.

"Please help us find Madeline," her sister, Megan Kingsbury, said during emotional comments at a press conference in April. "Her children need their mother. We need our daughter, our sister, our aunt and our best friend back."

Her sister described Kingsbury as a "hard-working and dedicated mother" who worked for the Mayo Clinic and was a graduate student.

Megan Kingsbury posted a video to social media following Fravel's arrest.

"The whirlwind is just starting all over again," she said. "This is definitely a silver lining. We're glad that he's in custody and he's not walking around as a free man anymore."

ABC News' Will McDuffie contributed to this report.