Handwriting samples collected from Pedro Bravo after his 2012 arrest were examined by an expert who testified in court Friday.
Thomas Vastrick, a forensic documenting examiner, explained to the jury how several unique features in Bravo's writing style were consistent with markings in his personal journals.
The journal, revealed in court earlier in the week, contained love letters over ex-girlfriend Erika Friman. Friman ended the relationship with Bravo to date Christian Aguilar, a mutual friend.
Prosecutors believe an obsession with her was Bravo's motive to plot to poison and kill Aguilar, a freshman at the University of Florida. The journals also contained a suicide note.
Jurors in the high-profile murder trial also heard from the first officer to come face to face with Bravo. The then-18-year-old walked into a police station on his own to report Aguilar missing.
"He was very cooperative and very wanting to assist in helping to find him," said Officer Timothy Peck.
"In fact, at times, did he volunteer information to assist in that capacity," asked prosecutor Brian Kramer.
"He did," replied Peck.
However, as Peck spoke in detail with Bravo, he saw signs of deception.
Peck said Bravo's descriptions of his last encounters with Aguilar were "very vague."
Bravo initially admitted to only being in a verbal argument with the friend he knew from high school at Doral Academy, but Peck said the story changed into a physical fight.
Aguilar's body was found weeks later dumped in a field.
While at the police station, Bravo gave detectives permission to search his SUV, where crime scene technicians found blood stains. They also found a scraped interior ceiling and a cracked windshield.
Police believe the SUV was the murder scene.
Defense attorneys deny Bravo killed Aguilar and opened up the possibility of reasonable doubt when it was their turn to question Peck.
"I have actually no idea," Peck said after being asked about the specific time of a second search.
"After the search with Officer Bierbauer, was the vehicle locked," asked defense attorney Michael Ruppert.
"I believe we did, but I can't tell you one way or the other," said Peck.
Precise details were left out of the initial police report, which means the officer had to rely on his memory for events that transpired nearly two years ago.
Jurors also heard from the two hunters who stumbled upon the decomposing remains of Aguilar.
"Something caught my nose," said Jesse Everidge, who was hunting in Levy County with his brother-in-law.
James Raines said he and Everidge followed the smell and stumbled across the body.
"The back of the skull you could see," said Raines. "Clearly it was not an animal."