Search warrants released Thursday said 44-year-old Kristine Kirk told dispatchers her husband bought and ate the candy before he started hallucinating and frightening the couple's three children.
Police say 47-year-old Richard Kirk also may have taken prescription pain medication before he began acting erratically.
It was not clear whether the pot influenced his behavior.
Authorities say Richard Kirk shot his wife in the head about 12 minutes into her call with 911.
Police say she told dispatchers her husband was getting a gun from a safe before a gunshot sounded and the line went quiet. The department is investigating whether police responded quickly enough.