Nobody can imagine why seemingly loving, devoted mothers would ever harm their own flesh and blood. But more than 200 women a year kill their children in the United States, according to the American Anthropological Association.
The shocking and unimaginable crimes of child-killers have gripped the nation for decades. Here's a look back at the famous cases of mothers accused of murder.
In 1983, Downs, a 27-year-old divorced postal service worker, told police that a "bushy-haired stranger" flagged down her car and shot her three children on a back road near Springfield, Oregon.
Her daughter Cheryl, 7, was dead on arrival at the hospital, and her other children -- Christie, 8, and Danny, 3, were clinging to life.
Downs' story about the stranger did not add up. Reading through her secret diaries, police found a motive: an obsession with a married man who didn't want her children. In February 1984, nine months after the shootings, they arrested her and charged her with one count of murder and two counts of attempted murder.
Downs' trial was a national spectacle that was later depicted in the TV movie "Small Sacrifices," starring Farrah Fawcett as Downs.
She was sentenced to life in prison plus 50 years. Downs will be eligible for parole in 2011.
In October 1994, Susan Smith drowned her two young sons, buckling them into their car seats and pushing the car into a South Carolina lake. The car sank with the sleeping children in the back.
Smith initially told police that a black man had hijacked her car and abducted the children. Americans desperately searched for the boys for nine days until Smith confessed that she killed her sons, Michael, 3, and 14-month-old Alex.
She was convicted of the two murders in July 1995 and sentenced to life in prison. A judge rejected Smith's appeal in March 2010. She is eligible for parole in November 2024.
In June 2001, Andrea Yates methodically drowned her five children in the bathtub in their Houston home. The case shocked the American public.
Yates told police and psychiatrists after the crime that Satan ordered her to kill sons Noah, 7; John, 5; Paul, 3; Luke, 2; and 6-month-old daughter Mary, to save them from eternal damnation.
Yates, a former nurse and the valedictorian of her high school, suffered from mental illness for years -- depression with bouts of psychosis, suicide attempts and hospitalizations.
In tapes of Yates' psychological evaluation, released exclusively to "Primetime" in 2006, she recalled details of the morning she murdered her kids, describing how she waited until her husband left to start filling the tub. "Drowning them" was "all I thought about," she said.
Yates was convicted of capital murder in March 2002, rejecting the defense argument that she was insane at the time of the killings. But in 2006, Yates was retried and found not guilty by reason of insanity and was committed to a state mental hospital.