New York (CNN) -- A man pleaded not guilty Thursday in the Father's Day shooting deaths of four people in a Long Island, New York, pharmacy robbery for painkillers, according to Robert E. Clifford, a spokesman for the Suffolk County district attorney's office.

Police said David Laffer has been accused of fatally shooting two employees at Haven Drugs in Medford as well as two customers before leaving with a large quantity of prescription drugs Sunday morning.

The attack was allegedly unprovoked, according to Police Commissioner Richard Dormer, who cited surveillance video that captured the shootings on tape.

Laffer's attorney, Mary Beth Abbate, noted that Laffer has no previous criminal record and has asked for a "reasonable bail," she said.

Police said Laffer later was identified -- despite wearing a phony beard, sunglasses and a cap -- after authorities received more than 400 tips from the public.

The 33-year-old Long Island resident had appeared on a list of pharmacy clients who received various drugs from the Haven Drugs store, Dormer said.

Laffer was also registered as owning a .45-caliber handgun, the same type of weapon used in Sunday's shooting, he added.

Dormer noted that evidence found at the scene allegedly linked Laffer to the shooting, but did not elaborate.

Laffer has been charged with first-degree murder and resisting arrest.

On Wednesday, police removed a bloodied and handcuffed Laffer from his home, and he appeared to have suffered trauma to his face.

"The officers had to use force" because Laffer became "extremely violent" during the arrest, Dormer told reporters.

Laffer's wife, Melinda Brady, 29, was also arrested and charged with third-degree robbery and obstructing governmental administration, authorities said.

"He was doing it maybe because he lost his job over my health," Brady told reporters during her arrest.

"I'm sorry that he did all this."

Both Laffer and Brady appeared "strung out" and "under the influence" at the time of their arrests, Dormer said. Brady has since been hospitalized.

The pair was arraigned Thursday at First District Court in Central Islip, Long Island.

Police identified the dead as Raymond Ferguson, 45, and Jennifer Mejia, 17, both pharmacy employees, as well as customers Bryon Sheffield, 71, and Jamie Taccetta, 33.

Mejia's death came days before her graduation from Bellport High School on Thursday, said school secretary Maryann Malcolm.

CNN's Rachel Garrett, Jason Kessler, Max Markham and Jordana Ossad contributed to this report.