John White is charged with killing 24-year-old Rebekah Gay at her home in October of last year and dumping her body in the woods.
Police say he confessed to killing the young mother as part of a sexual fantasy.
The plea agreement includes a required minimum sentence of no less than 45.8 years in prison. It also allows the court the discretion to impose more than 45.8 years on the minimum.
According to Risa Scully, the prosecuting attorney, Michigan passed the Truth in Sentencing law in 1998 which eliminates good time credit and requires offenders to serve the entire minimum sentence before being considered for parole. This means White will serve at least 45.8 years.
White, who was orginally charged with first degree murder, will be sentenced on April 18th in Isabella County.