A St. Paul man pleaded guilty Friday to first-degree premeditated murder and was immediately sentenced to mandatory life in prison, the Pioneer Press reports.

Steven Roger Johnson, 35, was accused of shooting his wife, Manya Jewel Johnson, 32, in the head at their St. Paul home Jan. 6 and then dismembering her body.

He was indicted on first-degree and second-degree murder charges last month.

According to the Pioneer Press, Steven Johnson described to his attorney how he and Manya Johnson got into an argument Jan. 6, which escalated to the point where the man retrieved a handgun he allegedly stole from her father and intended to "scare her."

After Manya Johnson threatened to leave him, he shot her, Steven Johnson said in court.

"I decided I needed to cover up what I did," Steven Johnson told his attorney, and proceeded to dismember his deceased wife, the Pioneer Press reported.

The couple's toddler son was at home during the alleged crime and Steven Johnson described to his attorney how he tended to the boy after the man shot his wife.

According to the Pioneer Press, the state agreed it would not oppose Steven Johnson applying for release after 30 years in exchange for his guilty plea. The judge in the case dismissed the second-degree murder charge against Steven Johnson as part of the plea agreement.