A woman whose husband is accused of gunning down four people in a pharmacy store holdup for painkillers pleaded not guilty Friday to charges she drove the getaway car, while funeral services were held for the youngest and oldest victims of the Father's Day massacre.

The morning after she was to have graduated from Bellport High School on Long Island, 17-year-old Jennifer Mejia's classmates wore caps and gowns in tribute at her funeral Mass.

Mejia was working as a clerk at Haven Drugs in Medford, Long Island, on Sunday when David Laffer walked in shortly after 10 a.m., authorities said. Without announcing a robbery, he opened fire, killing her, the pharmacist working behind the counter and two customers who unwittingly walked in on the carnage, authorities said.

He fled with a backpack full of oxycodone and other painkillers with his wife, Melinda Brady at the wheel, prosecutors said. They were arrested three days later at their home, a mile and a half from the pharmacy.

At Brady's arraignment on robbery and obstruction charges, assistant district attorney James Chalifoux called the killings "the most cold-blooded robbery-homicide in Suffolk County history."

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Brady, 29, was ordered held on $750,000 cash bail or $1.5 million bond, amounts her Legal Aid attorney said she would be unable to post. The attorney, Jeremy Mis, said Brady intended to testify at a grand jury proceeding set to begin next week.

The grand jury will consider expanding or upgrading charges against Brady and Laffer, prosecutors said.

Brady faces an obstruction charge for grabbing onto a police officer's leg while he was placing handcuffs on Laffer, authorities said.

According to a police department complaint, Brady admitted planning the robbery with her husband on June 18 but said she believed Laffer "would only threaten the pharmacist to steal drugs." She provided Laffer with a phony prescription written to her that he could use in the holdup, the complaint said.

Laffer, 33, was arraigned Thursday on first-degree murder and resisting arrest charges, and a court-appointed attorney entered a plea of not guilty for him. He was being held in the county jail on a suicide watch.

Police said he has refused to cooperate with their investigation and grabbed for an officer's weapon while being arrested. He was treated at a hospital for two black eyes and a bloody face.

Brady's arraignment was delayed until Friday while she spent a night in a hospital for an undisclosed medical condition. She implicated her husband after her arrest Wednesday.

"He was doing it because he lost his job and I was sick," she told reporters as she was escorted from police headquarters to a precinct holding cell. "He did it. He did all of this."

According to posts she made on the website Long Island Weddings before her 2009 marriage to Laffer, Brady told fellow brides-to-be on the site that she was in severe pain and taking different types of painkillers.

"I have been on pills after pills for this infection and it won't go away," she wrote. "I am not a depressed person or anything before this all happened. I was happy."

Laffer served in the Army from 1994 until 2002 and attained the rank of private first class, said Mark Edwards, a spokesman for the U.S. Army Human Resources Command in Fort Knox. While in the service, he worked as an intelligence analyst.

Neighbors of the couple, who lived with Laffer's mother in a sprawling ranch home with a built-in swimming pool in Medford, about 60 miles east of New York City, said they were shocked to learn he was suspected in the bloodbath.

At the funeral Mass for Mejia on Friday, several classmates walked in with a large water bottle filled with cash. Taylor Riley told reporters the students had collected the money at Thursday night's graduation ceremony to donate to the Mejia family. After the service, which was held in both English and Spanish, classmates in their caps and gowns -- red for the girls, blue for boys and white for honor graduates -- converged around her white casket, trimmed in gold.

"She's an angel in disguise now," Kristen Vasquez said.

A woman who didn't know the Mejia family said she came to the service in solidarity with her neighbors. "It's just a tragedy, just a tragedy," said Julie Deliso of East Patchogue. "No one should have to go through this at their age," she said of the teenagers grieving for their friend.

Also Friday, a private service was held for Bryon Sheffield, 71, who was picking up a prescription for his ailing wife, Sheila, when he was killed. The couple was to have celebrated their 50th wedding anniversary in July, relatives said.

The retired businessman was described as the family prankster who loved playing video games, Newsday reported.

A funeral Mass for Jaime Taccetta, a 33-year-old mother of two who was planning to be married later this year, will be held Saturday in Lake Ronkonkoma. Raymond Ferguson, a 45-year-old pharmacist who was working so a colleague could have Father's Day off, also will be remembered Saturday at a Mass in Forest Hills, Queens.