LAWRENCE — Mathew Borges and Lee Manuel Viloria-Paulino shared a fondness for nature, enjoyed watching how the lights played across the surface of the Merrimack River at night, and even hung out together on Nov. 18 — the day Viloria-Paulino disappeared — according to court records.
Borges is accused of stabbing his Lawrence High School classmate that night, decapitating the 16-year-old Viloria-Paulino, and mutilating his body. Borges, 15, who will be tried as an adult, was arraigned in Lawrence District Court Monday, where he pleaded not guilty. He is being held without bail.
Details of the crime were not discussed in court, and no motive has been offered for the killing.
Viloria-Paulino’s family and friends filled the courtroom amid a large police presence, and some craned to catch a glimpse of Borges while others wept. Some friends of Borges attended, but his parents, who were with him after his arrest, did not attend, officials said.
According to a police report, Borges told someone about the gruesome crime.
“Mathew told him he did something bad,’’ investigators wrote in a police report. “Mathew then told him that he stabbed a kid and cut his head off, killing him.’’
A surveillance video captured the two boys leaving Viloria-Paulino’s family home on Forest Street at 5:40 p.m. on Nov. 18, police said. That was the last time his family saw the teenager alive. The duo then walked to a spot on the riverbank familiar to the teens.
“[We] both like nature,” Borges reportedly told police, and they liked “the way the boat house across the river is lit up at night.”
Police said in the report that Borges told investigators that he and Viloria-Paulino smoked marijuana together on the night of the killing.
Viloria-Paulino’s body, dressed in a black T-shirt and black sweatpants, was found Thursday by a woman walking her dog. His head was found nearby, authorities have said.
Essex District Attorney Jonathan Blodgett said at a news conference Saturday that Viloria-Paulino’s body was so badly mutilated that the autopsy took 11 hours to complete. “This was a horrific, horrific murder,” Blodgett said.
Borges was arrested Friday, and his parents and his attorney were with him when he was booked on the murder charge. His attorney, Edward Hayden, said Borges is the oldest of five children, a sophomore at Lawrence High School, and worked part-time at Market Basket. Hayden declined to discuss the case.
At Lawrence High School, classmates said Borges showed no signs of being involved in his friend’s murder.
Classmates Nishia Torres, 16, and Aziah Vazquez, 17, described Borges as a quiet teenager with anger issues.
“He was scary,” said Vazquez, who added that Borges was friends with her brother. “He was negative to be around. He seemed mad at the world.”
“You don’t see him with a smile,” added Torres. “He would always get in a lot of fights.”
Viloria-Paulino’s family said Borges had been at their home just once, a few days before Viloria-Paulino went missing. They contend that Lawrence police insisted the teenager had run away, and that police failed to look for him after the family filed a missing persons report after he didn’t he return home that night. Police officials have not responded to the family’s allegation.
After the arraignment Monday, Viloria-Paulino’s mother, Katiuska Paulino, again raised the issue of whether police responded properly when notified in mid-November that her son was missing.
“I do want to ask a question, with all due respect, to the mayor, to the chief of police, to every police officer, detective, in our Police Department,’’ she told reporters. “If it was their kid, would they have waited two weeks to look for him?”
Lawrence police spokesman Detective Thomas M. Cuddy said Monday that “it was investigated as soon as possible, as soon as it was reported, within 24 hours.”
Lawrence police twice turned to social media for help in locating the missing teen, the first time on Nov. 20 when the department posted a photograph of the teen on Facebook and Twitter one day after he was reported missing to police.
State Police working with the Essex district attorney’s office were notified on Nov. 28 — 10 days after Viloria-Paulino went missing, said Carrie Kimball Monahan, spokeswoman for the district attorney’s office.
According to the Executive Office of Public Safety website, state law requires police departments to “immediately’’ react when a juvenile is reported missing to them, regardless of whether the child is a runaway, a victim in custodial kidnapping, or considered endangered.
“Whenever a parent. . . reports to any police officer or law enforcement official that a child is missing, such police officer or official shall immediately cause to be entered into the central register relevant information relative to said missing child,” the law reads. “Such police officer or law enforcement official shall also immediately undertake to locate such missing child.’’
Lawrence police Officer William Green told the Globe on Saturday that his department treats missing person reports like “nuisances” instead of something to be investigated.John R. Ellement and Evan Allen of the Globe Staff contributed to this report.