Seven-year-old Alec Mater and his six-year-old sister Lydia were found dead from gunshot wounds at their father's Surprise, Arizona home during a welfare check in May 2024. Their father, Brock Mater, age 34, shot both children in the head before fatally shooting himself; a rifle was recovered on his lap. The children's mother, who was going through a divorce, had been unable to reach them since Friday and called 911 after the school reported an unexcused absence; neighbors reported hearing what they thought were fireworks Sunday night, when police believe the shooting occurred. Mater had recently been undergoing mental health treatment and had a prior October 2023 mental-health crisis and an unsubstantiated DCS neglect report that also referenced domestic violence between the parents.
Contexts/Conditions
Is there any mention of child drug ingestion or overdose?
Is there any mention of a drowning incident (either intentional or accidental)?
Is there any mention of a firearm incident?
The fatality reports describe death "due to gunshot wounds," and the news article states "Investigators recovered a rifle on Mater's lap" and that the victims were "shot in the head."
Is there any mention of inappropriate supervision (e.g., child wandered off and drowned)?
Is there any mention of inflicted injury? (e.g. slapped, punched, kicked, choked)
The children died of gunshot wounds inflicted by their father. The preliminary report states the Department "determined their father, Brock Mater, inflicted the injuries to Alec and Lydia," who were "discovered deceased at their home due to gunshot wounds." The news article states police "found Mater and the two children dead from being shot in the head."
Is there any mention of malnutrition, starvation, or dehydration?
Is there any mention of medical neglect?
Is there any mention of a motor vehicle crash or incident?
Is there any mention of a murder-suicide incident?
The news article headline and text describe "an apparent murder-suicide," and the fatality reports state the father "inflicted the injuries to Alec and Lydia" and "was also discovered deceased at the home due to a self-inflicted gunshot wound."
Is there any mention of outdoor elements (including hot car deaths)?
Is there any mention of prenatal substance exposure (including fetal alcohol syndrome or neonatal abstinence syndrome)?
Is there any mention of sexual abuse?
Is there any specific mention of shaken baby or abusive head trauma?
Is there any mention of prolonged abuse or torture (including restraints, captivity)?
Is there any mention of an unsafe sleeping environment?
Individuals Involved
Was an adoptive parent or guardian involved in the death?
Was a biological father involved in the death?
The children's biological father, Brock Mater, killed them. The preliminary report states the Department "determined their father, Brock Mater, inflicted the injuries to Alec and Lydia."
Was a biological mother involved in the death?
Was a day care worker, babysitter, or nanny involved in the death?
Was a female paramour or friend involved in the death (e.g., girlfriend, stepmother)?
Was a foster parent involved in the death?
Was a male paramour or friend involved in the death (e.g., boyfriend, stepfather)?
Was another adult relative involved in the death? (e.g., grandfather, aunt)
Was a sibling involved in the death?
Child Characteristics
Was the child adopted?
Was the child homeschooled (including "cyberschooling") or taken out of school?
Was the child in foster care at the time of the incident?
Was the child living with relatives at the time of the incident (but not parents)?
Is there any mention of a neurological developmental child disability? (e.g., autism, intellectual disability, nonverbal)
Is there any mention of a physical child disability? (e.g., feeding tube)
Is there any mention of prematurity or low birthweight?
Is there a history of child protection reports prior to death (for this child or siblings)?
The fatality reports document a prior DCS report: "On October 20, 2023, a report was received alleging neglect to Alec and Lydia by Mr. Mater. The allegations were unsubstantiated... the case was closed on November 8, 2023."
Does the child have a history of foster care (but not in care at time of incident)?
Is there a history of a sibling death (separate incident from this death)?
Parent/Caregiver Factors
Was an adult charged or arrested for the child's death?
Is domestic violence by the parent/caregiver referenced?
The press statement notes "additional concerns regarding a domestic violence incident between the parents" in the October 2023 report. The news article also frames the case as "the second domestic violence situation involving children in Surprise in only a matter of days."
Is there any mention that the death occurred in a temporary shelter or while homeless?
Is an intellectual disability of the parent/caregiver referenced?
Is the mental health of the parent/caregiver referenced?
The news article states Mater "had recently been undergoing mental health treatment" and that officers had previously responded "due to a mental health crisis last October." The press statement notes "the father was experiencing a mental health crisis and expressing suicidal ideations."
Is a history of arrests or criminal charges for the parent/caregiver referenced?
Is substance use by the parent/caregiver referenced?
Notable Details
The summary report describes a systemic-review mechanism: under "A.R.S. § 8-469, cases with prior involvement with the Department within 3 years of the critical incident are reviewed by a multidisciplinary team (MDT)" with findings compiled into an annual report. The news article also highlights a systemic context—"the second domestic violence situation involving children in Surprise in only a matter of days," referencing a separate shooting of an infant (Jaxson) by his father days earlier, and a psychologist's view that "there were signs that were missed before the shooting."
These fields were populated by an AI model and may contain inaccuracies. Review the links and PDFs provided for verification before citing. Contact [email protected] to report any inaccuracies where corrections are needed.