Mathew Borges, now 18, was convicted of first-degree murder in Salem, Massachusetts on Tuesday – He was tried as an adult for the killing of Lee Manuel Viloria-Paulino, 16
He was tried for first-degree murder in Lawrence, Massachusetts, just outside of Boston
The high school student then aged 15, ‘flew into a jealous rage because his girlfriend was talking to a classmate’
The teen stabbed Viloria-Paulino 76 times, beheaded the boy and cut off his hands’ after sending chilling text message saying ‘I think of killing someone everyday and I smirk’
Prosecutors allege that Borges killed Viloria-Paulino in November 2016 when the two went to a riverbank to smoke pot
Viloria-Paulino’s body was found a month later by a woman walking her dog
Prosecutors detailed how Borges had become jealous that Viloria-Paulino was spending time with a girl he liked
Borges’ girlfriend at the time, Leilany Dejesus, testified that he was enraged with jealousy when he saw her talking to Viloria-Paulino at school
Prosecutors said text messages sent by Borges to his girlfriend read: ‘I think of killing someone and I smirk’
But his attorney argued that ‘the text messages do not prove that his client killed anyone’
Borges, who was then 15 but was tried as an adult, faces 25 to 30 years in prison for premeditated murder and extreme cruelty and atrocity
In the middle: Leilany Dejesus, Borges’ ex-girlfriend, took the witness stand. Weeping she testified that Borges flew into a rage when he saw her talking to Lee Viloria-Paulino
Borges was 15 years old when he allegedly killed fellow student Viloria-Paulino, beheaded him, cut off his hands, and then dumped the remains in the Merrimack River in November 2016.

On the night the murder, Viloria-Paulino, 16, and Borges went to the riverbank. Police said surveillance video captured the victim and Borges walking together toward the river.
Borges later told police that he and Viloria-Paulino had gone to the river to smoke marijuana but they later parted ways.
Four boys testified that they had plotted with Borges to rob the victim’s home that same night and steal his clothes, belts and PlayStation.
Borges was chosen out of the group as the person who should lure Viloria-Paulino to the river, the court heard.

Prosecutors said Borges killed the victim at the river while the other boys were carrying out the robbery. 
His family reported him missing the next day, according to WCVB-TV.
During opening statements of the trial on Monday, James Gubitose, the Essex County assistant district attorney, read a text message that Borges allegedly sent to a female friend.
‘I think of killing someone and I smirk,’ the text message read.
Mathew Borges [left], was 15, when he reportedly murdered his classmate Viloria-Paulino [right], 16, over a girl in in a gruesome assault in Nov 2015
He dumped his classmate’s body by the banks of the Merrimack River where it was found two weeks later in December 2016 by a woman walking her dog, according to MassLive.
Viloria-Paulino’s head was found close by but his hands were never found.
Borges was arrested in December 2016.
During the two-week murder trial, prosecutors detailed how Borges and the victim had been classmates at Lawrence High School at the time.
They argued that Borges had become jealous that Viloria-Paulino was spending time with a girl he liked.
The girl, Leilany Dejesus, testified during the trial that Borges was consumed by rage and jealousy after seeing her talking to the victim.
Borges was convicted for beheading and the dismemberment of 16-year-old Lee Viloria-Paulino [photo] near a Massachusetts riverbank in November 2016
The victim’s family watched the first day of the trial in Lawrence, Massachusetts in late April
‘It’s all I think about everyday but I control myself…I like the sound of it – the idea of causing pain in someone getting in my way or causing me pain.’
Prosecutors say that Borges told other teens who were later interviewed by police: ‘I killed him. He’s dead.’
Borges is allegedly seen on surveillance video walking toward the river with Viloria-Paulino on the night of his death.

Prosecutors said that while Borges and Viloria-Paulino were out by the river, a group of four of Borges’ friends broke into Viloria-Paulino’s home.
The teens allegedly told police that Borges planned to kill Viloria-Paulino.
Prosecutors allege that a note found by investigators reveals how Borges planned to carry out the crime.
‘Go chill with him in his crib alone… bring duffel bag, wear bags on shoes, wear clothes you don’t care about,’ the note allegedly read.
Investigators are seen at the crime scene after Lee Viloria-Paulino’s body was found near the Merrimack River in Dec 2016. he had been reported missing two weeks earlier.
After killing Viloria-Paulino, the court heard that Borges then called his group of friends and told them that he had killed his target, saying: ‘I killed him. He’s dead.’ 
The four boys have all admitted to breaking into Viloria-Paulino’s home.
Borges’ attorneys had argued during the trial that there was no physical evidence to link their client to the death.
But prosecutors argued that there was a ‘mountain of evidence’ against him, including texts he had sent to friends and ex-girlfriends, as well as journal entries that appeared to point to premeditated murder.
‘I think of killing someone and I smirk,’ one of his earlier text messages to a female friend read.
‘It’s all I think about everyday but I control myself…I like the sound of it – the idea of causing pain in someone getting in my way or causing me pain.’
Borges is scheduled to be sentenced on July 9. 

But Borges’ attorney, Ed Hayden, said the text messages and the note cited by prosecutors do not prove that his client is a killer.
Hayden said that Borges broke into Viloria-Paulino’s home, but he did not kill him.
‘There is no murder weapon, there is no tools to dismember a body, there are no fingerprints, there is no blood, there is no DNA,’ Hayden told WBZ-TV.
The text messages that prosecutors cited were ‘loaded with the f-bomb the n-word, weed and sex. That’s what that group chat was about,’ Hayden said.
‘In these thousands of texts and messages there is no evidence that Matthew killed Lee.
‘Anything incriminating is referring to the house break.
‘There is nothing in all these messages.’
Borges, who was 15 at the time but was tried as an adult, faces 25 to 30 years in prison for premeditated murder and extreme cruelty and atrocity.
The jury deliberated for two days before handing down their verdict.