ROCHESTER HILLS (WWJ) – An Oakland County grandmother accused of killing her adult son and his infant daughter will spend between 25 and 50 years in prison.

Sylvia Marie Majewska (Photo: Oakland County Sheriff’s Office)

Sylvia Majewska of Addison Township, who was previously found unfit for trial, underwent two psychiatric exams before she pleaded no contest to murder charges in the deaths of 29-year-old Daryne Gailey and his 7-month-old daughter, Charley Hendrick.

During the sentencing, Oakland County Judge Denise Langford Morris said she was almost speechless at the brutality of the murders that occurred three years ago in Gailey’s Oxford Township home.

Authorities say Majewska, who was 65 years old at the time, cut Gailey’s throat, killed the baby with blows to the head, and then tried to kill herself by slashing her arms.  She was found bleeding from her left wrist into a bucket, with a box cutter on the table next to her.

At the scene, investigators said they discovered handwritten notes in which Majewska revealed she’d planned the killings.

According to Sheriff Michael Bouchard, Majewska apparently “came to the conclusion that the son and the child would be better off if they weren’t alive.”

Majewska told the judge she had challenges taking care of her son, who had learning disabilities and suffered from seizures.

© Copyright 2017 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.