Aiden Fucci: Child who posted arrest selfie to be tried as adult over murder of 13-year-old Tristyn Bailey

Charge also upgraded to first-degree murder

Police have arrested Aiden Fucci, 14, who has been charged with the murder of 13-year-old Tristyn Bailey (St Johns County Sheriff’s Office)

The teenager accused of killing Tristyn Bailey will be tried as an adult and has had his charge upgraded to first-degree murder.

Aiden Fucci, 14, is accused of killing the 13-year-old cheerleader, who was found dead, with “horrific” stab wounds, on Mothers’ Day in St. John’s County, Florida.

Mr Fucci was arrested shortly after the discovery of the teenager’s body, and allegedly posted an arrest selfie to snapchat from the back of a police car, which he captioned: “Hey guys has anybody seen Tristyn lately”.

The teenagers were classmates at Patriot Oaks Academy in St. Johns, but police said they are not aware of whether the pair knew one another, the Daily Beast reported.

The St. Johns County Sheriffs Department had previously announced that the teenager had died of a blunt force trauma by stabbing.

“This is a cold-blooded murder of a 13-year-old young girl who did not deserve to die,” St Johns County Sheriff Rob Hardwick told local news outlet WJXT.

“That being said, I don’t wanna mention the number of times [Tristyn was stabbed], but it is horrific. It is horrible,” Mr Hardwick added. “And the word accident is nowhere involved in this case.”

At a press conference announcing the upgraded charge and decision to try Mr Fucci as an adult, State’s Prosecutor RJ Larizza provided further details of the decision behind the charge.

“It’s a sad decision, and a sad state of affairs, but it was clear to us after we looked at what happened, that it was not only appropriate to charge the defendant as an adult, but it was really the only choice that we can make,” he said.

“The bottom line is that premeditation, could be inferred, certainly from just the sheer number of stab wounds that Tristyn Bailey had to suffer.”