Erika Wigstrom appeared to adore her baby boy long before he was born. When someone rear-ended her car, she rushed to the emergency room to make sure the baby was unharmed. She proudly posted photos of her “baby bump” on social media. And when she was four months pregnant, she took to Twitter to write a message of devotion to her unborn child.

“I’ll do what ever I have to, as long as you have a good and happy life,” she wrote on March 20, 2012. “My heart and my love.”

Two years later, however, Wigstrom was behind bars, accused of murdering her baby boy to end his suffering from Down syndrome and a heart defect.

On Tuesday, the horrific family drama came to a head when Wigstrom pleaded guilty to killing her own son by injecting hand sanitizer into his feeding tube. A Louisiana judge handed down the harshest sentence possible: 40 years in prison without probation.

By pleading guilty to manslaughter, Wigstrom escaped first-degree murder charges.

The case has shaken the small town of Belle Chasse, a suburb of New Orleans and one of the last stops on the Mississippi before it melts into the Gulf.

Plaquemines Parish is generally a peaceful place. In 2013, the year Wigstrom began posting photos of her baby bump on Twitter, the parish only saw one killing. The next year would see the same tally, only this time, it would be Wigstrom’s work.

Little is known about Erika Wigstrom, a cherubic young woman who had barely turned 19 by the time she gave birth to her son, Lucas Ruiz.

What is known comes from traces left behind on Twitter. Her account suggests a pregnancy with high hopes punctuated by a painful discovery.

From the look of her Twitter feed, Wigstrom joined the social media service simply to post updates on her pregnancy. In her first tweet, she wrote that she was going for a walk to fight the baby weight she was already putting on.

A month later, she posted a worried tweet from the emergency room after she was rear-ended in her car.

She joked about her food cravings, how long her pregnancy seemed to last and how her baby hated it when she laid on her stomach. “My belly button is about to pop,” she wrote on May 6, 2012 alongside the hashtag #preggoproblems.

Yet, she also posted selfies with her baby bump and wrote a promise to protect her unborn child.

“Mommy loves her little prince,” Wigstrom wrote.

But Wigstrom’s little prince was born with serious disabilities: Down syndrome and holes in his heart. The holes could be mended with surgery, but the Down syndrome could not.

Lucas Ruiz was staring at a difficult life. So, too, was Wigstrom.

That’s how Erika Wigstrom’s promise to do whatever she had to give her child “a good and happy life” turned into a plan to kill him.

The first attempt came in October of 2012, when Lucas was in the hospital. He was just two months old and already having breathing problems.  Doctors told Wigstrom and the boy’s father, teenager Cesar Ruiz, that their son needed heart surgery.

While in the hospital, Lucas suddenly began having seizures. When doctors examined the boy, they discovered he had a blood-alcohol content of .289: three and a half time the legal driving limit for an adult.

When authorities questioned the parents, Cesar Ruiz confessed to giving the boy rum but said it was just as a pain reliever. When police questioned Wigstrom, however, she told detectives Ruiz had said their son “would be better off dead, and that he wished [the child] would die during his upcoming heart surgery,” according to an arrest report obtained by the Times-Picayune.

The seizures damaged the baby’s brain and Ruiz was charged with second-degree cruelty to a juvenile, the newspaper reported,

Eventually, Ruiz confessed to trying to kill his son, according to police.

“I heard him sobbing, crying like subtly and detective Sacks consoling him, saying ‘It’s alright, you can let it out,'” Lt. Curtis Matthews testified in court before a judge ruled the confession was admissible.

The already dark family saga soon blackened even further, however.

On January 24, 2014, while Ruiz was still in jail, Wigstrom called police to say that Lucas was having a medical emergency. Emergency medical technicians arrived to find the 17-month-old “breathless and pulseless,” according to the Times-Picayune. The boy was rushed to the hospital but declared dead on arrival.

The boy died “while cradled in the arms of his beloved mother,” according to his obituary.

Lucas’s short life may have been over, but the misery was not.

An autopsy, completed five weeks later, revealed something too terrible to be a coincidence: the baby’s blood had once again been spiked with alcohol (to .28 percent, or three times the legal driving limit).

When Plaquemines Parish Sheriff’s detectives called Wigstrom in for questioning on March 11, 2014, the mother quickly confessed to killing her child. She murdered her baby by putting Germ-X, a hand sanitizer containing ethyl alcohol, into his feeding tube, she said.

Wigstrom didn’t want Lucas to suffer anymore, she told authorities. Nor did she regret her decision.

“From what I gathered from the detectives, they basically said she had no remorse,” Plaquemines Parish Sheriff’s Office spokesman Cmdr. Eric Becnel told the Times-Picayune.

Wigstrom went further, however, claiming that it was she — not Ruiz — who gave Lucas the alcohol in Oct. 2012. And instead of rum, she used an alcohol-based perfume that she dumped into his feeding tube over the course of several days.

A Plaquemines Parish grand jury indicted Wigstrom on March 26, 2014. Instead of going to trial on a charge of first-degree murder, she pleaded guilty to manslaughter.

On Tuesday, Judge Kevin Conner sentenced her to the maximum, 40 years in prison without parole, the Times-Picayne reported.

Whether or not her killing really was an act of mercy, her confession has helped one person. On Aug. 31, prosecutors reduced the charge against Cesar Ruiz to criminal mischief, a misdemeanor, according to the Times-Picayne. A judge ruled Ruiz guilty of the lesser charge but, having spent more than a year in prison, Ruiz was released.

He walked out of jail a free man, but no longer a father.