Susan Smith's ex-husband says she casually apologized after killing their two sons

David then recalled asking Susan why she killed their two sons. "She said, 'I don't know why, but I'm sorry," David told the show.

In October 1994, when Smith was 22, she strapped Michael and Alexander into the back seat of her car and watched as she let the vehicle roll into John D. Lake in Union County.

Former Union County prosecutor Tommy Pope, now a South Carolina state representative, previously told Fox News Digital that Smith was having an extramarital affair at the time with the son of a local, wealthy business owner.

After she was denied parole during a hearing last year, Susan appeared to become emotional and cry.