ATLANTA — The state child welfare agency that investigated whether a South Carolina father was capable of caring for his five children before he allegedly killed them and dumped their bodies in rural Alabama has itself been under scrutiny in recent months, facing allegations of botching similar cases that resulted in child deaths.

The department’s leadership will be asked to justify its handling of the case of the five siblings in a State Senate subcommittee hearing on Tuesday.

“We intend to ask a lot of questions,” said Senator Joel Lourie, a Democrat and member of the panel. “This is a tragic, horrific situation.”

The scrutiny comes as Gov. Nikki R. Haley of South Carolina, a Republican who has faced sharp criticism for more than a year over her handling of the department, runs for re-election. Her Democratic opponent, Vincent Sheheen, who trails badly in polls in an overwhelmingly Republican state, had been running television ads before the five siblings’ deaths saying the department had failed to protect vulnerable children.