Possible - curious who gets so angry that early in the morning ? She knew his dad was out of town so she had time I’m guessing if this was premeditated - something isn’t adding up for me so far ...This got me thinking about a scenario.
Perhaps she lost her temper with Gannon, and injured him in some way. If those injuries left marks, she knew she wouldn’t be able to explain it to Gannon’s father.
So in order to cover up an act of abuse, she killed Gannon.
jMO