RIVERHEAD, N.Y. (CBSNewYork) – A man accused in the stabbing death of a Long Island high school student has pleaded not guilty.

Adam Saalfield, 21, appeared in court in Riverhead Thursday after being indicted for second degree murder. He is being held without bail.

Prosecutors said Saalfield used a knife-like object to slash the neck of his neighbor, 18-year old Maggie Rosales, in Huntington Station last month, WCBS 880’s Sophia Hall reported.

Authorities said he came up from behind and grabbed the high school student, who did not hear him coming because she was wearing ear buds and listening to music.

Prosecutors said they have a strong case against Saalfield, including DNA evidence from a blood trail found outside Saalfield’s home along with video surveillance.

“We have the DNA evidence,” said prosecutor Raphael Pear. “It’s a very strong case. We have video of the crime as well.”

But defense attorney John LoTurco said there is no motive, no confession and said no murder weapon was found. He said Rosales’ gang member ex-boyfriend could be the real killer.

“He had motive to commit this crime in that she recently broke up with him. He was seeking revenge for that breakup,” LoTurco told Hall. “Which is in contrast to Adam, who has no motive to commit this crime.”

Police said Saalfield and Rosales did not have a previous relationship.

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