The man arrested in connection with the deadly stabbing of a Walt Whitman High School student is being held without bail.

According to police, 21-year-old Adam Saalfield murdered 18-year-old Maggie Rosales, and left her body on Lynch Street in Huntington Station on Oct. 12.

Prosecutors say Saalfield walked up behind Rosales and slit her throat twice.

Police say they have the attack on surveillance video and have DNA evidence tying him to the crime.

There is no word yet on a possible motive.

Saalfield attended Valley Forge Military College and lived with his mother in a Huntington Station house just six homes away from Rosales. The victim's family and Saalfield's attorney both said the two did not know each other.

Court records show Saalfield was arrested just six days after the murder for possession of a hypodermic needle and allegedly told police that a friend who used heroin had left them in his car. Prosecutors say police took his DNA during that arrest and it matched the DNA left at the Rosales crime scene.

Saalfield pleaded not guilty at his arraignment Thursday. His defense attorney John LoTurco says he will "provide Adam with the most vigorous and zealous defense possible."