A Wisconsin woman believes her husband sleepwalked into a river and drowned after taking sleeping pills, WLUK-TV FOX 11 reported.

Cherie Merkes said her husband went to bed early on Friday because he wasn't feeling well, and when she woke up Saturday morning, he was nowhere to be found.

After calling emergency rooms and the doctor, Merkes called the police, who found his car in an abandoned lot along the Fox River in Oshkosh that afternoon, the station reported.

Michael Merkes' wallet was found in the glove compartment, the doors were unlocked and keys were in the middle console.

"The fact that the car was not locked tells me he was not conscious of what he was doing because he was so paranoid about the credit cards in his wallet," said Merkes.

Police continue to search the river and surrounding area for her husband, but Merkes believes the sleeping medication he was taking caused him to sleepwalk, drive to the river while still asleep and fall in, FOX 11 reported.

"In the depth of my soul I know that's what happened to him," said Merkes, adding her husband would never run away and no money was missing from their bank accounts.

Click here to read more on this story from WLUK-TV FOX 11.