Houston Police Department spokesman John Cannon said Roy Garza was arrested on child endangerment charges after he allegedly left his grandson in a park alone during a drunken stupor, the Houston Chronicle reported Saturday.
The child was found unharmed by a delivery man following Friday's alleged incident and placed in temporary foster care.
The child's mother, Yvette Diallo, said she was puzzled by her father's alleged behavior, saying he typically is a great grandfather to all her kids.
"I'm confused," Diallo told the Chronicle. "My dad is a good person. My kids love him. It hurts me to see him in jail, but I'm hurting because I miss my baby."
Garza was watching his grandson while Diallo was working, a routine situation for the family.
The Chronicle said Child Protective Services officials are due in court Monday to ask for custody of the child while the matter is investigated.