Joseph Facundo, 18, and Tony Escobar, 17, were arrested Friday while trying to cross the border. Harris County sheriffs deputies say both men and another woman went to Russell Lopez's house in Katy to buy marijuana, but decided to rob him.
They allegedly beat Lopez to death with a hammer then tied up the children. The kids were not hurt in the attack.
Facundo and Escobar are facing capital murder charges.
Another suspect, Amber Thornton, 22, is already in custody.