MENASHA - Kelly Rousseau of Dale can fathom only one explanation for the disappearance of his 55-year-old wife, Jill, and his 21-year-old daughter, Jordan.

He believes they were abducted.

"Nothing else makes sense," Rousseau said during a press conference outside Oasis Wellness Center, which is owned by the family and where the two women were last seen driving away at 4 p.m. Sunday.

"And then, I'm a problem-solver," he said, "so if that's the case, then who did it and why? I have no idea. No idea."

RELATED: What we know about the Rousseau family so far

Rousseau said his wife’s credit cards haven’t been used since the disappearance.

The Outagamie County Sheriff's Office is investigating the case.

"It's our main focus right now," Sgt. Nathan Borman said. "It's everything we're working on. We have everybody committed to this."

Kelly Rousseau reported his wife and daughter missing Monday morning. He said he had been gone since Thursday to attend a cousin's funeral in northern Minnesota and was driving back to Wisconsin when he last spoke to his wife on the phone about 1:15 p.m. Sunday.

He said his wife told him she was going to do some gardening and stop by the Oasis Wellness Center, 600 Century Oaks Drive, to pick up some papers. He said he had no further contact with his wife or daughter.

Rousseau said security cameras near the Oasis Wellness Center show Jill and Jordan arriving at the business at 3:45 p.m. Sunday and leaving 15 minutes later, turning north on Racine Road. They were in the family's 2011 Ford Expedition King Ranch sport utility vehicle, he said.

The sheriff's office said the SUV is maroon on the top and tan on the bottom. It has a Wisconsin license plate number of 650-PPM.

Rousseau said he returned home from his trip about 8:15 p.m. Sunday and noticed his wife and daughter were gone. He called his wife's cellphone, which rang in the house.

"All of a sudden, I went, 'Oh, that's kind of weird. She didn't take her cellphone,'" he said.

His daughter's cellphone also was in the house. He said he assumed his wife and daughter were sleeping at the Oasis Wellness Center, which has two futons in the basement. The building houses his wife's wellness center and his daughter's sewing alteration business.

RELATED: Authorities search for two Dale women missing since Sunday

Borman said Kelly Rousseau is cooperating with investigators and is not believed to be involved with the disappearance. He said investigators have "very good knowledge of where he was at and where he has been."

"He is doing everything we ask of him," Borman told USA TODAY NETWORK-Wisconsin. "We have no reason to suspect him in any way at this point of any sort of foul play."

No search warrants have been carried out in the case, Borman said.

Rousseau said at the press conference that he has nothing to hide. "I want my daughter and my wife back,” he said.

Borman said investigators don't know if the disappearance is voluntarily or if it involves foul play.

"We just know we have two adult women who we cannot locate," he said. "It's out of the norm for them to be missing like this. Obviously, that's very concerning."

Borman said the family doesn't appear to have any financial or marital problems. He said investigators have checked multiple areas for the women and are looking into every lead. "We've had leads to follow up on here in Wisconsin and in other states, and nothing has panned out yet," he said.

Rousseau described his wife as analytical and his daughter as a social butterfly who loves to dance and be around people. He said their disappearance was "so out of character."

"There's just so many things that don't add up," he said.

Johanna Kopecky, Jordan’s close friend, described Jordan as bubbly, talkative, funny, outgoing, friendly and kind. She said she sent a text message to Jordan on Saturday morning that didn’t elicit a response. She learned they were missing Monday.

“The past couple of days have been a blur,” Kopecky said. “It doesn’t feel real at all.”

Adam Boutwell, a friend of Kelly Rousseau, pleaded with the public to search for the Rousseau SUV. He said hundreds of people have volunteered to help.

"We really need to find that car," Boutwell told USA TODAY NETWORK-Wisconsin. "There's not evidence here (at the wellness center). There's not evidence at the home. We need the car for the next piece."

Borman said the search for the SUV has gone nationwide. "We're getting indicators from other states, but nothing that leads us to this vehicle," he said.

Kelly Rousseau said "thousands of people" are praying and looking for his wife and daughter.

“There’s been a huge outpouring,” he said. “The support is amazing. I never dreamed that I would be in front of cameras saying, ‘Where’s my wife and where’s my daughter?’ You never think it’s going to happen to you.”

A prayer vigil for the Rousseaus will be held Wednesday at Calvary Bible Church, 1450 Oakridge Road, Neenah. The doors will open at 6 p.m.

Anyone with information on the whereabouts of the women are asked to contact Sgt. Mike Fitzpatrick by phone at 920-832-5279 or by email at Mike.Fitzpatrick@outagamie.org.

People also may call the Outagamie County dispatch center at 920-832-5000 and reference incident number 19-026089.

Contact Duke Behnke at 920-993-7176 or dbehnke@gannett.com. Follow him on Twitter at @DukeBehnke.