(NewsNation) — Madeline Kingsbury has been missing since March 31 when she and the father of her children dropped off their kids at day care. She didn’t show up for work, and she didn’t return at the end of the day to pick up her children.

The Winona, Minnesota, Police Department said it’s not prepared to identify a suspect or person of interest at this time, but police are desperately trying to piece together what happened next.

“Madeline was just a hard-at-work mom … she took care of her two babies. She had started graduate school in January,” Kingbury’s mother, Krista Naber, said In an interview with NewsNation. “Things were finally looking up for her.”

Thousands of searchers have converged in the area around Winona. Volunteers on foot, on horseback, K-9 teams and submersible drones are all searching for any sign of the 26-year-old.

“We believe Maddi’s disappearance is involuntary, suspicious and we are all concerned for her safety,” said Winona Police Department Chief Tom Williams. 

As the police trace back steps, they start with Kingsbury and the father of her children, Adam Fravel, dropping off their children around 8 a.m. on March 31.

The day care said that was not unusual.

Police said Kingsbury and Fravel arrived back at Kingsbury’s home around 8:15 a.m. Around that time, Kingsbury responded “LOL” in a text string to her sister.

Then, around 10 a.m., Fravel said he took Kingsbury’s Chrysler Town & County minivan to run errands. Fravel claims that was the last time he saw Kingsbury. He said he returned around 1:30 p.m., and she was gone.

“Inside the residence, investigators located Maddi’s phone, the jacket she had been wearing earlier in the morning, along with her wallet and ID,” Williams said.

Kingsbury’s sister, Megan, said Monday on NewsNation’s “CUOMO” that “never in a million years” would Madeline have abandoned her kids.

“Negative chance. If she ever wanted a break, she would have come to my house and bring the kids. She wasn’t ever one to just walk off and disappear for anything,” Megan Kingsbury said.

Police said a van matching Kingsbury’s was seen driving west and then south through Winona and Fillmore counties in the direction of Mabel, which is listed on Facebook as Adam’s hometown, and then back north again later.

The van was last seen being driven down a county road.

“All of this occurred between approximately 10 a.m. and 1:30 p.m.,” Williams said.

Police shared maps on social media to focus the search area and are asking residents to check their properties and outside cameras.

“Especially along and around the routes previously mentioned, we’re asking you to walk your property. Check out buildings and have a good look around for any signs that someone passed that way or for signs of a disturbance,” Williams said.

Fravel issued his first public statement last week, denying allegations that he was involved in Kingbury’s disappearance. He also said he’s cooperated with authorities, including multiple interviews.

“I did not have anything to do with Maddi’s disappearance. I want the mother of my 5-year-old and 2-year-old to be found and brought home safely. I want that more than anything,” Fravel said.

Police said numerous search warrants have been served, and police have processed the van to collect forensic evidence, but they remain tight-lipped about anything they’ve found.

“We’re hopeful that evidence collecting will lead in the right direction to who is responsible,” Naber said.

As the community searches for evidence and answers, Kingsbury’s story has captured the attention of figures like Minnesota Sen. Amy Klobuchar, who visited the search location.

“When you think of her story of leaving her kids at that day care — ready to go to work, a mom who loves her children, it just resonates with everyone, and people want to know what happened here,” Klobuchar said.

Kingsbury’s family said they remain committed to finding her.

“We’re trying to stay strong for Maddi, and we hope to have some good news that we have found her really soon,” Megan Kingsbury said.

Madeline Kingsbury’s family is offering a $50,000 reward for information about her disappearance.

If you have information that could help investigators call 1-800-222-TIPS or visit www.crimestoppersmn.org.