RIVERHEAD, N.Y. (AP) - A prosecutor says a New York man accused of killing two pharmacy employees and two customers during a holdup for prescription painkillers spent days looking for a target, and staked out the drugstore the night before the incident.

David Laffer appeared in court Thursday on charges stemming from the June 19 massacre at Haven Drugs in Medford. He has pleaded not guilty to five counts of first-degree murder and four counts of criminal use of a firearm.

Suffolk County District Attorney Thomas Spota (SPOH'-tuh) says chilling security video shows the defendant shooting the victims and then stuffing pills into his backpack amid the "deadly silence."

He says it also shows a victim, 17-year-old Jennifer Mejia, talking about helping her mother shop for a dress to wear to her upcoming high school graduation.

(Copyright 2011 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.)