Cathleen Alexis said today that she does not know why her son, Aaron, did what he did and she will never be able to ask him.
The mother read a statement at her home in New York. She concluded, "My heart is broken."
The 34-year-old Aaron Alexis opened fire Monday before he was killed in a shootout with police.
Authorities say he had been suffering several serious mental problems including paranoia and a sleep disorder.