In May 2024 in Surprise, Arizona, six-year-old Lydia Mater was found dead alongside her seven-year-old brother Alex and their father, 34-year-old Brock Mater. The children had been visiting their father during an ongoing divorce. Concerned when the school reported both children absent and the mother could not reach Brock, a welfare check was requested.

Officers forced entry after receiving no answer and discovered all three with fatal gunshot wounds. Investigators determined Brock Mater inflicted the injuries on Lydia and Alex and then died by a self-inflicted gunshot. A rifle was found across his lap; neighbors had reported loud noises the previous evening they first thought were fireworks. The case was closed with authorities saying no other suspects were involved.

If anyone knew Lydia or Alex, or has information about that night in May 2024, please share what you know with the Surprise Police Department.