The man accused of murdering Mimi Dietrich at their Guelph home has pleaded guilty to second-degree murder.

Stephan Dietrich confessed in court Thursday to killing his wife Seble, who went by the name Mimi, and encasing her body in concrete.

She was last seen alive in July 2014.

Her disappearance was not immediately treated as suspicious but friends and members of her church told CTV they had their suspicions.

Almost a year later, in June 2015, Stephan was arrested and charged in her death.

The couple lived with their three children at a home on Vancouver Drive.

That’s where Stephan said that he attacked his wife, hitting her in the head five times with a shovel.

He claimed the murder wasn’t planned.

The couple fought over a phone bill, the court heard, immediately before the attack.

Stephan put her body in concrete and then told their three children that their mother left them and didn’t love them anymore.

According to the agreed Statement of Facts, just days after the murder Stephan drove to his mistresses’ home in Toronto in Mimi’s car. He then drove back to Guelph and left the car at a café Mimi owned.

He also typed up a letter, pretending to be Mimi, and placed it in a friend’s mailbox. It read: “I’m gone and will not be back. I have committed adultery and I am now pregnant. Help my husband to find a woman who is better than me.”

The court also heard how Stephan moved his mistress into his home with his three children in the months after Mimi’s death.

Stephan will be sentenced on November 22.

A second-degree murder conviction comes with an automatic life sentence. Both the crown and the defense agree he should serve at least 22 years before being eligible for parole.

The judge also warned Stephan that it’s likely he’ll be deported back to Germany upon his release.