Steven R. Johnson fatally shot and dismembered his wife in their St. Paul home on Sunday after she announced plans to leave him and take their 18-month-old son.

Johnson, 34, used a saw to dismember Manya J. Johnson in the couple's shower. He then placed the 32-year-old woman's body in several plastic bins and stored them in a friend's garage in White Bear Lake, according to second-degree murder charges filed against him on Wednesday in Ramsey County District Court.

According to the charges, Johnson confessed, telling police he and his wife argued Sunday. He said he had been drinking, and shot Manya in the head with a handgun. He said he cleaned the house to hide evidence.

The friend in whose garage Johnson put the bins was unaware of his actions, the complaint said, but Johnson later told him what he'd done. The friend alerted White Bear Lake police about 3 p.m. Monday, who notified St. Paul police.

The killing shocked neighbors and friends, who considered the Johnsons "the perfect couple" and good neighbors.

However, Anoka County court documents from his 1996 conviction for aiding and abetting criminal sexual conduct describe a troubled teen who had chemical dependency issues. A psychologist diagnosed the 18-year-old as "particularly defective in his capacity for empathy" and as having "a pathological sexual adjustment that is not likely to be improved very much by the time he leaves prison."

According to Anoka County documents on the crime, Johnson and two friends tricked the woman into climbing into Johnson's car in Coon Rapids. They drove to an isolated area near Sand Creek Park, where his friend, Kyle D. Scott, also 18, grabbed the woman and Johnson handcuffed her.

The second friend fled, according to the complaint. Johnson and Scott tore off the woman's clothes, taped her mouth shut and sexually assaulted her multiple times. They also simultaneously raped her. Johnson threatened to kill her, and implied that he had a gun.

The crime was so heinous that Johnson, considered the mastermind of the attack, received twice the guideline sentence -- 17 years and two months in prison with supervised release and sex offender registry until 2018.

Johnson was released from prison in February 2008. Within a few years, he and Manya were living in the 1400 block of Sheldon Street in the Como neighborhood, renovating their quaint two-story and planning for the birth of their son.

Johnson met with a probation officer monthly, and never violated the terms of his release.

Manya, who earned a bachelor's of science in psychology at Pacific Lutheran University and a master's in counseling psychology at Bethel University, worked in marketing operations for Target Corp., where she was considered witty, outgoing and an outstanding worker. When she didn't show up for work Monday, her co-worker and friend Claudine Starkey said she searched for Manya with Steven, who was "playing along with the ruse" until police arrived at the couple's home about 4:30 p.m. Monday.

Judge Gary Bastian set Johnson's bail at $2 million. Prosecutors Yasmin Mullings and Ana Christie told the judge that the high bail was needed because of the heinous nature of the act, and because there are indications that their child was present during the dismemberment.

Manya's family declined to comment, but her sister Leah Twite posted a statement on Facebook thanking friends for their condolences. Johnson's family did not return messages seeking comment.

Staff writer Joy Powell contributed to this report. Chao Xiong • 612-270-4708 Twitter: @ChaoStrib