A woman who drowned her newborn daughter in a Burnsville bathtub in 2005 was sentenced Monday to nearly 25 years in prison.

Samantha Anne Heiges cried as she read a lengthy statement in court, saying it wasn't her plan to kill her daughter Sidney.

Heiges, who turned 23 Monday, claimed that she had been punished enough, saying she felt shame every day for what she did, Dakota County Attorney James Backstrom said.

A jury had convicted Heiges of second-degree murder in September after less than four hours of deliberation despite the fact that the baby's body was never found.

"To my knowledge, it may be the first one in Minnesota where a [murder] conviction was secured without a body," Backstrom said.

Investigators did not look for the body at Pine Bend Landfill because the search was unlikely to yield the infant's remains and would have been dangerous because of flammable methane gases, he said.

Backstrom said a witness who came forward mid-trial provided testimony that was key to the conviction. That witness said Heiges confided while pregnant that she planned to kill the baby and then confirmed after killing the baby that she had done it.

Heiges' own statement to police in 2007 acknowledged her guilt. And DNA samples from blood at the apartment, while not conclusively linked to Heiges, did have traces from three people, suggesting a baby and parents.

"It was a complex, difficult case and we're pleased that we were able to obtain a conviction and bring her to justice for a very tragic crime," Backstrom said.

According to the criminal charges, Heiges gave birth to the girl in a Burnsville apartment on May 5, 2005, and then held the baby underwater in the bathtub as she gasped for air.

Heiges told investigators she did it because her then-boyfriend, Erik Ryan Matlock, had threatened to kill her and her daughter if Heiges did not get rid of the baby. But a witness said the pair had planned to kill the baby after she was born.

Heiges said Matlock threw the body down a garbage chute after she had put it in a shoebox lined with towels.

A man dating Heiges called police in 2007 after she told him she had killed the baby.

Backstrom said Heiges, who knew of but did not take advantage of a law that allows mothers to leave unharmed babies at hospitals within 72 hours of birth, will be eligible for parole after 16 1/2 years. She has another daughter, born in February 2008, he said.

The case against Matlock, who is charged with aiding an offender, is pending.

Katie Humphrey • 952-882-9056