Police in Anoka reportedly entered Jansen's house and found his wife's body with gunshot wounds. Investigators also said they found an unloaded handgun and its receipt.
Jansen, according to the complaint, told officers that he was surprised he proceeded with the alleged homicide. He reportedly told them: "I guess I don't have to worry about a divorce."
His wife served him with divorce papers around Thanksgiving, but the pair both remained in the home. Mary Jo Jansen's family said she decided to move out on Saturday.
A GoFundMe for the slain woman states she "was a beautiful mom, daughter, sister, aunt, niece, cousin, friend and coworker who will be missed immensely by all who knew her."
Jansen, according to online records from the Anoka County Sheriff's Office, is being held on $1 million bail on second-degree murder charges.
The Associated Press contributed to this report.