Amanda “Mandy” Marissa De La O McCauley was a beloved mother, daughter, sister, and friend whose warmth and playful spirit brought laughter to countless lives. Born in Sioux City, Iowa, on November 5, 1983, the 42-year-old was the youngest of four children and was known for her deep love for her family, friends, music, and dancing. After attending West High School, she pursued her passion for dentistry at Western Iowa Tech Community College, graduating in 2011.
Mandy became a valued team member at Lilly Family Dentistry, where she formed meaningful connections with her colleagues and the families she served.
Above all, Mandy’s most cherished role was being a mother to her son, born in 2013, and her daughter, born in 2018. Her children were the center of her world, and she devoted herself completely to them. Friends and family remember her as fiercely loyal and caring, a woman who enjoyed watching movies and quoting her favorite lines to bring humor into everyday moments. Her kindness and laughter touched everyone who knew her, and her memory is treasured by her surviving children, siblings, grandmothers, and many nieces, nephews, aunts, uncles, and cousins.
The morning of Saturday, September 26, 2026, turned tragic when Sioux City police responded to a report of a shooting at a residence on the 3100 block of Douglas Street, near Grandview Park. The call came from inside the home around 8:15 a.m. When officers arrived, they discovered a devastating scene. Inside, they found three people deceased from gunshot wounds: Amanda McCauley, her 76-year-old mother, Yolanda Guerra Koon, and Amanda’s 42-year-old husband, Andrew McCauley.
The Sioux City Police Department launched an immediate investigation into the deaths. Detectives determined that Andrew McCauley had shot and killed his wife, Amanda, and his mother-in-law, Yolanda. Investigators concluded that as police officers were arriving at the home, Andrew McCauley died from a self-inflicted gunshot wound. The case was classified as a murder-suicide, and the investigation remains ongoing, though authorities have identified the deceased shooter as the sole perpetrator.
The violent loss of three family members sent shockwaves through the Siouxland community. A neighbor who lived across the street from the home described the event as highly unusual for the area and stressed the importance of neighbors coming together in the wake of such a tragedy. The focus of community support quickly turned to Amanda’s two young children, ages 8 and 13, who lost both of their parents and their grandmother in the incident.
In the days following the shooting, the Crittenton Center in Sioux City, where a relative of the victims worked, began collecting donations to help with funeral expenses and to provide for the children's future. The organization stated, “These children’s lives have been forever changed and we want to show them that they will be taken care of by not only their family but the Siouxland community.” The center accepted gift cards, checks, and cash to ensure all funds went directly to the care of the children.
A visitation for Amanda was held on Sunday, October 4, 2026, at Mohr & Becker - Hunt Funeral Home in South Sioux City, followed by a Funeral Mass on Monday, October 5, at St. Michael's Catholic Church. She was laid to rest at St. Michael's Cemetery. Amanda was preceded in death by her mother, Yolanda, who was killed alongside her, as well as her grandfathers and other beloved relatives. Though her life was cut short, her family holds onto the memory of her strength, loyalty, and love, which they vow will live on through her children. As of September 2026, the case is considered closed as the primary suspect is deceased.
