There are no easy answers to preventing massacres such as that carried out by Nikolas Cruz at a Florida high school: not on guns, not on mental health, not on responding to warning signs.

One thing about Cruz does appear clear, however. Had his mother, a single parent, not died last year, his homicidal impulses might have been kept in check.

Lynda Cruz died in November. Her son went to live with the parents of a classmate, who told reporters they had no idea he was dangerously disturbed.

They knew he owned multiple guns but didn’t know he had a key to the family lock box where they were stored. They knew he was depressed but were happy his grades were fine and thought he was doing OK. It’s not necessarily their fault; he did a good job of hiding his activities from them.

“We had this monster living under our roof, and we didn’t know,” the mother of that family told a reporter.

But he may not have been a monster under the handling of Lynda Cruz, who knew her son had serious problems. He had discipline problems at school, so much so he was expelled last year.

Investigators have learned his mother seemed to hold his violent tendencies in check. She made him follow through on therapy and ensured he took his medicine. When he scrawled a swastika and a racial epithet on his book bag, she forced him to erase them.

It appears that after she died, no one else understood the extent of his homicidal hatred. The pain of losing one’s mother and only parent could drive any teenager into dangerous territory, and Cruz was already playing with fire.

Loving family members can make a major positive difference in someone’s life. At the same time, dysfunctional family relations can sometimes do more harm than good. Again, no simple answers, but kinship runs deep — deeper than we can even find words to describe — and the relationship between a mother and child is primal. When it vanishes, it’s not easy or quick to find a substitute for its knowledge, understanding, checks and balances, and undefinable power of love.

Will that knowledge help deal with young people like Cruz in the future? We hope so, but it is not a sweeping answer to the problem of mass murders. Sadly, there is none.