(CNN) -- A 14-year-old Florida teen accused of gunning down his parents faces manslaughter charges and will be tried as an adult, the Collier County State Attorney's Office said Wednesday.
Alexander Thomas Crain has been in custody since his December 9, 2010, arrest, authorities said. He has a Thursday afternoon hearing in Naples.
Since the teen's arrest, prosecutors had been determining appropriate charges, which could have included second-degree murder.
Crain now faces two lesser charges of manslaughter with a firearm.
"We had hoped that the prosecutor, based on the doctor's evaluations, would charge this young man as a juvenile," said Brian Bieber, Crain's attorney. "However, we are pleased in a sense that prosecutors took into account all the information provided not only by us but the doctors and decided to charge him with manslaughter rather than intentional homicide."
The younger Crain is accused of shooting Thomas Crain, 40, and Kelly Crain, 39, at their home in Golden Gate Estates, Florida, a suburb of Naples.
Police have not released a possible motive.
"We are exploring all mental health issues," Bieber said, "because obviously this case presents a unique set of facts, and there is a great deal of facts that are simply out of the ordinary, to put it mildly. The (Crain) family expressed their position to the prosecutors that the case should remain in juvenile court. The prosecutors felt otherwise."
If convicted, Alex Crain could face mandatory prison time.
However, the judge could eventually sentence him as a juvenile, in which case he would be spared from serving his sentence in an adult prison.