(Newser) – Cook County sheriff's detectives watching Antoinette Briley waited for her to finish her cigarette. She dropped it, and they picked it up, giving them the DNA sample they needed. Briley, 41, is now charged with two counts of first-degree murder in the deaths of her two newborn twins, WBBMreports. The boys were found in June 2003 after being left in a trash bin. They had been born alive, an autopsy found, then died of asphyxiation. The investigation at the time didn't lead to any arrests, but the technology has changed. DNA tracing led to the identification of Briley as the twins' birth mother. "Seventeen years ago we wouldn't have made this case this way," a sheriff's official said Saturday, per CNN.