Fla. teen Wayne Treacy's defense says he had PTSD when he allegedly beat girl

(CBS/AP) FORT LAUDERDALE, Fla. - Florida teenager Wayne Treacy is scheduled to go to trial next week for allegedly attacking a girl outside a middle school in 2010, leaving her with permanent brain injuries.

The defense says that Treacy, then 15-years-old, was suffering from post-traumatic stress disorder stemming from his brother's suicide.

If convicted of first-degree attempted murder, Treacy could be sentenced to 50 years in prison. If not, he could still spend years at a state mental institution, according to legal experts and attorneys.

The defense claims that Treacy became enraged by a series of text messages between him and Josie Lou Ratley, the girl who was brutally beaten.

In several texts, Ratley calls Treacy a "rapist," to which he finally responds, "Why are you trying to get yourself killed? I will find you. I will mess you up, you will regret crossing me," according to the AP.

According to CBS Miami, after receiving a text message telling him to "go visit" his dead brother (who was found hanging from a tree in front of a church five months earlier), Treacy reportedly grew upset and wanted to confront Ratley.

Evidence shows that Treacy did computer searches on how to kill someone barehanded efficiently.

"I'm going to jail for murder," Treacy said in one text to a friend, according to investigative records.

Most of the friends said they didn't take the threats seriously.

Prosecutors say that Treacy wore martial arts fighting gloves and his brother's steel-toed boots and rode his bike to the middle school, where he asked his girlfriend, Kayla Manson, to point out Ratley.

Numerous witnesses say Treacy grabbed Ratley by the neck, knocked her to the ground and began stomping and kicking her. A teacher managed to knock Treacy away from the girl, who was by then lying unconscious in a pool of blood.

The teacher, Walter Welsh, then hustled Treacy into the school office and waited for police and paramedics to respond.

Welsh said it was clear immediately the attack was planned. "He was on a mission," Welsh said.

A defense expert has testified that Treacy was most likely in a state of detachment, which can last for hours or days, making him unaware of what he was doing.

But Nova Southeastern University law professor Robert Jarvis says convincing a jury of that might not be easy.

"In the end, I think the defense fails in this case because lots of people lose a loved one and still function without engaging in a crime and jurors know that," Jarvis said to the AP.

Ratley, who is recovering, reportedly has no memory of the attack or the text messages that started it all, according to CBS Miami. Manson is charged as an accessory to the crime for allegedly helping Treacy find Ratley.