Jury selection is underway for the mother charged with poisoning her son to death.

Lacey Spears, 27, is charged with depraved murder and manslaughter in the death of her 5-year-old son, Garnett Paul-Spears.

Authorities say Spears intentionally fed her son salt at toxic levels, all the while documenting his declining health on social media. They say she also searched the Internet for information on the dangers of sodium in kids.

Read more from the Associated Press:

The boy's sodium levels rose to a dangerous point with no medical explanation, prosecutors said, leading to a swollen brain, seizures and death. They believe his single mother, who was sharing his hospital room at Westchester Medical Center, administered salt through a feeding tube into Garnett's stomach.

All the while, she was keeping followers up to date with 28 online postings in the last 11 days of his life, noting his death with, "Garnett the great journeyed onward today at 10:20 a.m." She had tens of thousands of entries over Garnett's lifetime, many about his doctor and hospital visits.

"My Sweet Angel Is In The Hospital For The 23rd Time," Spears tweeted on Nov. 9, 2009, adding a sad-faced emoticon. "Please Pray He Gets To Come Home Soon."

Fox News legal analyst Lis Wiehl and former prosecutor Doug Burns discussed the case today on “Happening Now.”

Wiehl said attorneys could bring in an expert to argue that Spears has Munchausen by proxy, which she explained is basically an insanity defense. But Burns noted that attorneys don’t seem to be using that defense.

Watch more above.