Mary Lou Caldwell Lett, 86, of Cape Girardeau died Friday, April 25, 2014.

Mary Lou was born to Ernest and Edith Lyle Lightner Caldwell at their home in Cape Girardeau. Mary Lou was the youngest of eight children.

Her father, Ernest, owned and farmed Devils Island. He died while Mary Lou was in the first grade, and the family moved to McClure, Ill. After severe flooding in the area, the family returned to Cape Girardeau.

Mary Lou graduated from Cape Girardeau Central High School in 1946. She held several jobs while attending Central.

She had one sister and six brothers. Five of her brothers served in World War II.

Mary Lou's first job was with Walgreens, and she also worked for Woolworths and Tinkoff.

The summer before her senior year her aunt, Ruby Caldwell, hired her to work at a secret military plant on the second floor of the Ford Groves building. Mary Lou's job involved soldering copper and silver transistors. A requirement for this position required skill and accuracy due the strict specifications for the parts.

Mary Lou was recognized for her quality work, and later it was learned these components were used for atomic bombs that were used in World War II.

After high school graduation she worked for Southeast Missouri Telephone Co. as a telephone line draftsman and worked directly for the engineer. The company was acquired by Southwestern Bell, where she continued her position.

Mary Lou married Thomas Harddie Lett Jr. in Piggott, Ark., on Dec. 13, 1952. They had three children, Thomas H. Lett III, Scarlett Lynn Puls and Paul Allen Lett.

Mary Lou joined Daughters of the American Revolution, Nancy Hunter Chapter, on Oct. 12, 1978, and was a member for 36 years. She held the positions of vice regent, historian and registrar.

It was in this association where her passion for genealogy was able to flourish. She was a tireless historical researcher and prided herself in doing quality work in an age when computers were not yet widely used.

Survivors include a daughter, Scarlett Puls and husband Charles Puls of Cape Girardeau; a son, Paul Lett of Cape Girardeau; a grandson, Allen T. Lett of Cape Girardeau; and a granddaughter, Selina M. Lett of Rolla, Mo.

She was preceded in death by her husband, Tom, and a son, Thomas H. Lett III.

Visitation will be from 3 to 6 p.m. today at Ford and Sons Mount Auburn Funeral Home.

The service will be at 10 a.m. Monday at the funeral home, with the Rev. David Conley officiating. Burial will be in Cape County Memorial Park.

Online condolences may be shared at fordandsonsfuneralhome.com.