One person is under arrest in connection with the death of a Lawrence teen whose decapitated body was found on the banks of the Merrimack River. The Essex District Attorney's Office said a search warrant was executed in connection to the murder of Lee Manuel Viloria-Paulino by police at 12:45 a.m. at a residence on Oxford Street and arrested 16-year-old Mathew Borges. Borges is expected to be arraigned Monday and will be charged as an adult. "This is a horrific, horrific murder" Jonathan Blodgett said at the press conference. "We were completely and totally committed in our resolve to bring this matter to justice and I am pleased to say that we were able to do that." Authorities have not determined any motive at this time. Viloria-Paulino's body was discovered by a woman who had been walking her dog on Thursday. Authorities said the woman called 911 after locating the body, and when first responders arrived they said they found the victim's head nearby. Mayor Dan Rivera said the homicide was "not a random act" and said the public was not at risk for additional acts of violence. The family of Viloria-Paulino spoke Saturday before the announcement of an arrest being made, and gave emotional testimonies about the case of the missing 16-year-old. "(He) was a lovely kid that had done nothing bad to no one," his mother, Ivelisse Cornielle, said. "He grew up in a family that has taken care of him in a lovely manner." Hundreds of people gathered for a vigil Friday night that honored the life of Viloria-Paulino.