Lorie Hentges, of Brick Township, had been indicted on a murder charge by two separate grand juries investigating the death of a 72-year-old heart patient at Jersey Shore University Medical Center in April 2007.
Authorities alleged she caused Alvin Flamenbaum's death by administering an unprescribed drug to him.
Monmouth County prosecutor Luis Valentin said the medical and toxicological evidence in the case is complicated and subject to differing interpretation.
"We have concluded that imprecision and certain omissions in the collection, preservation and analysis of the evidence in this case render the state incapable of carrying its burden of proof at a trial," he said. "The interests of justice require that the indictment be dismissed."
Hentges' attorney, Alton Kenney, did not immediately return a call seeking comment.
Flamenbaum, of Toms River, had been diagnosed with congestive heart failure. He was being moved to a rehabilitation center on April 12, 2007, when he began complaining of shortness of breath and other symptoms. While en route to the hospital in Neptune, he stopped breathing.
He was placed on a respirator, and his family decided to discontinue lifesaving measures when his condition was diagnosed as terminal.
But after being taken off the respirator, Flamenbaum started breathing on his own.
On April 14, a nurse who was primarily responsible for Flamenbaum's care returned from a lunch break to find Hentges in Flamenbaum's room, authorities said. Shortly afterward, his vital signs worsened and he died.
An autopsy listed the cause of death as the acute effects of an unprescribed paralytic drug, and the case was classified as a homicide.
Hentges was not assigned to care for him, authorities said.
She denied administering the paralytic drug, and countered that Flamenbaum actually died from a fatal dose of morphine and other drugs. Toxicological studies confirmed that Flamenbaum had morphine and a number of other drugs in his system at the time of his death.
Hentges, 41, was indicted by a grand jury in 2008, but her lawyers got that indictment dismissed, alleging that prosecutors had committed procedural errors. A new grand jury indicted her again on a murder charge in March 2009.
She was fired from the hospital in October 2007.
