WHITE PLAINS, N.Y. (CBSNewYork/AP) — Opening statements began Tuesday in the murder trial of a young mother accused of fatally poisoning her 5-year-old son with salt and documenting his decline on social media.

Lacey Spears, 27, of Scottsville, Kentucky, is charged with depraved murder and manslaughter in the death last year of Garnett-Paul Spears.

Prosecutors say Spears fed her son large amounts of salt through a gastrointestinal feeding tube, causing brain swelling, seizures and death. They believe she administered the salt in his room at Nyack Hospital after he was admitted for seizures.

As CBS2’s Lou Young reported, the boy had a special feeding tube in his abdomen that was left over from an illness he had in infancy. The state said it was medically unnecessary, but provided Spears with the ability to sicken her son at their Rockland County home and then fatally poison him during subsequent hospital stays.

Spears wiped away tears as Westchester County Assistant District Attorney Doreen Lloyd called her a calculating child killer, WCBS 880’s Marla Diamond reported.

Lloyd said Spears purposely sickened her son for “attention and sympathy.”

“Although her son was incredibly special, he was not sick — he was not sick until his mother made him sick,” Lloyd said.

Video recordings will show the mother watching for the sodium to take effect, then summoning help when her son starts writhing, Lloyd said.

Defense attorney Stephen Riebling said there’s no evidence or eye witnesses to back up the prosecution’s claim, adding Spears showed the care and support expected of a mother.

Lloyd told jurors they would see hospital video showing mother and son twice going into the bathroom and then see Garnett become ill soon afterward both times. He died of high sodium levels that caused swelling of the brain.

But the bathroom is out of the range of the camera, and Riebling noted that no one saw Spears feed her son salt.

He said, in context, Spears’ actions show a caring mother.

He implored the jurors to “set aside emotion.”

Riebling also appeared to blame the hospital near the Spearses’ Chestnut Ridge home, noting it was only there that a high sodium level was detected.

He said the prosecution case was “riddled with reasonable doubt.”

Garnett’s death ended a short life filled with doctor and hospital visits that his mother tirelessly documented in thousands of postings on Facebook, Twitter, MySpace and a blog.

Many of the postings will be in evidence, along with Spears’ online research into the dangers of sodium in children and hospital records from New York, Florida and Spears’ native Alabama. Also in evidence is a feeding bag prosecutors believe was used to hold the salt — and which they say she tried to hide in a cover-up after Garnett’s death.

Defense attorneys fought the introduction of much of that evidence.They have insisted that there will be no mention of Munchausen by proxy, a disorder in which caretakers secretly harm children to win sympathy. Some experts believe that disorder fits Spears’ actions.

The defense said no decision has been made on whether Spears will take the stand in her own defense.

The trial is expected to last about three weeks.

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