JACKSONVILLE, Fla. -

A hearing Friday morning in the murder case of a 13-year-old became a debate over whether state sentencing guidelines could prevent Cristian Fernandez being tried on a charge of first-degree murder.

The boy was inside the courtroom as his attorneys argued on a motion to dismiss the murder charge against Fernandez. Defense attorneys said a June ruling by the United State Supreme Court bars a person younger than 18 from being sentenced to death or a mandatory life sentence, but those are the only two sentences prescribed for first-degree murder under Florida's sentencing guidelines.

"Cristian can't know the punishment he's facing because both punishments that are under the statute -- one death, the other life without parole -- have been declared unconstitutional," defense attorney Bryan Gowdy said.

Defense attorneys argue only the Legislature can make a decision on what an appropriate punishment would be.

The state agrees that death and life without parole is not an option, but says Fernandez should still face trial on a charge of first-degree murder in the death of his 2-year-old half brother. The boy -- who was 12 at the time of his arrest -- also faces a sexual abuse charge involving an attack on a 5-year-old half-brother.

Prosecutors argue the court must consider reverting back to the old guidelines for teens, requiring less mandatory prison time.

"This defendant should be on notice that he is facing a life sentence with a minimum-mandatory sentence, which is 25 years and eligible for parole after that point in time," prosecutor Mark Caliel said.

Last month, Judge Mallory Cooper threw out the statements Fernandez gave to Jacksonville police in both cases, ruling a boy that age without his parent or legal counsel could not understand his Miranda rights and he did not understand the consequences when he waived them.

Cooper plans to take time to determine what an appropriate ruling might be. Both sides agree that depending on her decision, coupled with the opinions of judges around Florida, all juveniles in a similar situation as Fernandez could be affected.

"If the judge agrees with us and other judges in the state agree with her, it would prohibit the state from prosecuting any child under the age of 18 for first-degree murder," Gowdy said.

"The main focus here should be, what remedy is available to the court to avoid a hiatus in the law?" Caliel said.

Cooper said it would likely take three weeks to review case law before she makes a ruling on the motion to dismiss the murder charge. She set the next hearing for Oct. 8.

While charged as an adult, Fernandez is being kept at the juvenile detention facility.

"I think he's doing fine, and you know, he's holding up the best as can be expected for someone his age, facing this type of situation," Gowdy said. "He's got a good support team now that I don't think he had before."