Houston (CNN) -- Back in 1982, Chelsea McClellan -- just 15 months old -- needed immunizations.
It was routine stuff, so Chelsea's mother took her to a local clinic in Kerrville, Texas. What happened there was anything but routine.
That's because Genene Jones was the nurse on duty. Chelsea's mother recalled the day.
"She gave her her first shot in her left thigh and she immediately started gasping for air," said Petti McClellan-Wiese. "Gave her another one, and she immediately just went limp and quit breathing."
In the chaos of rushing Chelsea from the clinic to the hospital, Jones somehow slipped into the ambulance and gave the little girl a third shot.
McClellan-Wiese would learn later that the nurse had injected her daughter with a drug called Succinylcholine, which causes muscle relaxation and short term paralysis. It stopped Chelsea's heart.
Jones was convicted of infanticide and sentenced to 99 years in prison for killing Chelsea, plus 60 years for injuring another child.
She maintains that she did nothing wrong.
For Chelsea's parents, the verdict was bitter sweet. Their daughter was gone but her killer would spend the rest of her life behind bars.
At least that's what they thought.
But it turns out, Jones is set to walk free in a matter of a few years.
She is scheduled to be released from prison as early as May 2018 because of an old Texas law designed to prevent prison overcrowding.
The Mandatory Release law allows inmates convicted of violent crimes between 1977 and 1987 to be automatically released if their "good behavior" credit plus their time served equals their sentence. The law was changed in 1987 to exclude violent criminals, but it isn't retroactive.
So now McClellan-Wiese and Andy Kahan, a victim's advocate for the city of Houston, are desperately trying to find other mothers whose babies may also have been killed by Jones.
A new conviction could keep her locked up.
Kahan says that two mothers have already reached out to him, including Marina Rodriguez.
Rodriguez lost her son in 1981 after, she says, Jones gave him a shot at a San Antonio clinic. At just 5 months old, he had a heart attack and died.
"All of a sudden he turned blue, and all of a sudden, I started hearing code blue. And then of course they put me to the side because I'm a young mommy and I'm freaking out," she said.
Back then, Rodriguez was 15 years old. She couldn't read and was too young to afford a lawyer. Her parents were migrant farmers.
When asked how she would feel if Jones were to walk free, she said she couldn't contemplate the possibility.
"She's not getting out! She's not going to get out! If my son has to be exhumed to prove that she murdered him, then that's the step we'll take. They're not dealing with a little girl anymore, this is a woman now," Rodriguez said.
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