Mary E. Frederickson, age 69 of Belleville passed away on Tuesday, February 24, 2026 at UW Hospital in Madison, WI.  She was born on September 24, 1956 in Milwaukee, WI the daughter of Robert and Beulah (Edwards) Sieger.  After graduating from high school Mary continued her education at the University of Wisconsin earning a degree in horticulture.  She would make her way to Colorado where she lived and worked for several years.  While in Colorado, Mary made a career change to begin working with computers and computer programming.  She would return to Wisconsin in the early 80's, where she operated her own computer programming business.  She was united in marriage to Thomas Frederickson on May 1, 1996 in Las Vegas, NV.  After Tom passed in 2009, Mary met Bruce Hefty in 2011 and the couple resided in Belleville together.  As Mary's health declined, she retired from computer programming and working part time at Jung's Garden Center.

Mary is survived by her companion Bruce Hefty, brother Don (Muggs) Sieger, nieces, nephews, and cousins.

She was preceded in death by her parents, husband Thomas Frederickson, brothers Robert (Georgeann) Sieger and James Sieger, and best friend Joette Edgar.

A visitation will be held from 11:00 a.m. to 1:00 p.m. on Monday, March 9, 2026 at the Becker-Beal Funeral Home, 109 Greenway Cross, Belleville, WI.

A time of remembrance will conclude the visitation at 1:00 p.m. on Monday, March 9, 2026 at the Becker-Beal Funeral Home in Belleville.

Bruce would like to thank and commend the staff at Four Winds Manor for the kind and compassionate care given to Mary.