Tristyn Bailey's body was found in a remote wooded area on Sunday night, and her classmate has been charged with second-degree murder
Tristyn Bailey
Tristyn Bailey
| Credit: Courtesy Tanya White

The Florida teen accused of killing 13-year-old Tristyn Bailey allegedly changed the story he told police several times — and authorities say that they later found his clothing stained with blood.

According to an arrest report obtained by First Coast News, the 14-year-old suspect told the police several contradicting stories while he being questioned. The arrest report alleges he made several "admissions" of guilt.

The arrest report also alleges that deputies found a security video that showed two teens — now believed to be the suspect and Tristyn — walking east on a suburban street at approximately 1:45 a.m. on Sunday morning. The video later showed just one person — believed to be the suspect — holding a pair of shoes while walking west around 3:27 a.m.

Tristyn Bailey
Tristyn Bailey
| Credit: sjso

Tristyn was found dead in a remote wooded area at about 6 p.m. on Sunday. She died of "force trauma by stabbing" and her cause of death was ruled by the medical examiner as a homicide, the St. Johns County Sheriff's Office announced on Tuesday.

"We will continue to investigate this case fully and will begin transitioning this case to the State's Attorney Office," the sheriff's office said in a statement.

Officers executed a search warrant on the suspect's home, and say that they found clothes matching the boy's outfit observed in the video surveillance. Some of the items have tested positive for the presence of blood.

The suspect — whom PEOPLE is not identifying because he is a minor and it is not known whether he will be charged as an adult — was a classmate of Tristyn's.

Tristyn Bailey
Tristyn Bailey
| Credit: gofundme

After the girl's disappearance on Sunday, the suspect allegedly took a selfie in the back of a patrol car and posted it on Snapchat. He was displaying a peace sign and captioned the photo, "Hey guys has anybody seen Tristyn lately?" A sheriff's spokesperson confirms that the boy in the photo is the suspect.

Authorities have not discussed a possible motive in her killing.

The suspect has not yet entered a plea, and is being held in a juvenile detention facility. His attorney has not returned PEOPLE's messages for comments.