CHICAGO (CBS) — The mother of a 6-year-old boy who was shot and killed in Aurora nearly 20 years ago said it would break her heart if the man convicted of killing her son gets a new trial, as the case went before the Illinois Supreme Court on Wednesday.

A panel of the Illinois Appellate Court has ordered a new trial for 38-year-old Mark Downs, who was convicted of murder in the 1996 shooting death of 6-year-old Nicholas “Nico” Contreras.

Prosecutors have appealed that ruling to the state’s highest court, and Nico’s mother, Sandy Contreras, traveled to Springfield on Wednesday to hear arguments in the case.

“It’ll break my heart to go through it again 19 years later,” she said.

She said, no matter how hard Downs might try to get out of his conviction, he’s a coward thinking he has a second chance at freedom.

Contreras said she is her son’s voice.

“Even though my son lost his life on December 10th of 1996, he still has his voice,” she said.

Prosecutors have said Downs fired a gun into the window of the home of Nico’s grandparents, thinking his uncle – a rival gang member – would be there. Nico was sleeping at the time, and was struck by two bullets. His uncle no longer lived at the house.

Downs was sentenced to 70 years in prison, but last year, the Appellate Court overturned his conviction, finding the trial judge improperly instructed the jury when it asked him to define reasonable doubt. The jury asked if reasonable doubt was “80 percent, 70 percent, or 60 percent,” but the judge said it was up to them to define for themselves.

The appeals court said, by asking for a specific percentage, the jury showed “it was already contemplating a standard less than the reasonable-doubt standard required under law,” and by telling the jurors the definition of reasonable doubt was up to them, the judge “gave the jury clear license to continue down its mistaken pathway of equating reasonable doubt to some percentage of confidence.”

While the Supreme Court heard arguments on the matter Wednesday, it likely will be weeks, if not months, before the justices rule.