A Texas woman will serve at least nine years in prison for drowning her 3-month-old granddaughter in what the defense said was a misguided effort to teach the infant to swim.

Gabriella Sigler must serve half of the 18-year sentence imposed Thursday before being eligible for parole. Sigler had pleaded guilty to a charge of injury to a child in the 2005 death of little Melody Sigler.

She was watching the baby when she allegedly put her in a friend's pool. She had allegedly told her son earlier that she was teaching Melody to swim like she had seen on a TV show about "water babies."

Defense witnesses testified Sigler was suffering from bipolar disorder. But police said Sigler admitted to using drugs the night before and
drinking wine the morning Melody died.