On Friday night, a child waited with his younger brother and sister for their mother to return home, authorities said.
Saturday was his ninth birthday, and their mother had left at 9 p.m. Friday, saying she was going to buy his present, they said.
Instead, 29-year-old Kristina Hope Wright stayed out drinking with a male friend, then spent the night at his home, said Lexington County Sheriff James R. Metts.
After several 911 hang-up calls from Wright's home starting at 7:32 a.m. Saturday, deputies arrived to find the children alone, Metts said.
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The 9-year-old had fed his 2-year-old sister and 5-year-old brother a breakfast of cold sausage and bread, said Maj. John Allard, Sheriff's Department spokesman.
The 2-year-old was "distressed" at having worn the same dirty diaper overnight. But "they weren't hysterical or crying. Under the circumstances, they were pretty composed," Allard said.
Deputies were waiting when Wright arrived smelling of alcohol at 8:32 a.m.
"She didn't seem surprised there were deputies at her house. The only time she showed emotion was when we told her she was under arrest," Allard said.
Wright was charged with three counts of unlawful conduct toward a child by a legal guardian. She was released after posting $30,000 bail Sunday.
The Department of Social Services took all three children into protective custody. Police determined there were no responsible adults to care for the children.
Allard said Wright's children weren't able to tell them if their mother had left them home alone before.
Wright has no criminal record, according to State Law Enforcement Division records.
It's an unusual case for police.
"I don't recall anything like this in my time with the Sheriff's Department," Allard said. We've had other cases where children were left alone for short periods of time but not like this."
Often a charge of unlawful conduct toward a child stems from an abuse and/or neglect situation.
In 2007, Columbia police charged husband and wife Morris E. "Gene" Porter and Carol Ann Cannadywith unlawful neglect toward a child after their 3-year-old son tested positive for cocaine.
In 2006, Miama Rebecca Kromah was sentenced to 10 years in prison after police say she cut her 3-year-old son's genitals.
In 2005, Linda Denise Titus, 38, was arrested and charged with unlawful conduct toward a child. Titus had abandoned her 14-year-old daughter in a wooded area on March 3, 2004, near a church, according to the Richland County Sheriff's Department. Church members became concerned when the girl showed up at the church unkempt.