Prosecutors face a heavy burden when trying to convict pill-pushing doctors of causing patient deaths.
In 2011, only six people were convicted and sentenced in federal court for distributing a controlled substance causing death, according to the U.S. Sentencing Commission.
Federal prosecutors Friday charged Dr. William Conway, of Baldwin, with improperly prescribing hundreds of prescription oxycodone pills to two of his patients who later died of overdoses.
The government's burden: showing not only that the prescriptions were improper but linking them with the deaths and delving into what the doctor knew or should have known, experts said.
"It's very, very uncommon. It's very, very uncommon because it's very, very unusual for prescription drugs to result in a death," James Cohen, an associate professor at Fordham University School of Law, said about the charge.
"I think that's a big leap," he added.
To make its case, the government must prove that a doctor provided the drug outside of the scope of a legitimate medical purpose, said Kevin Keating of Garden City, a former prosecutor who now practices criminal defense law.
"They have to establish the linkage between the improper prescribing and the resulting death," Keating said.
"These are difficult cases to prove beyond a reasonable doubt," he added.
Giovanni Manzella, 34, of Long Beach, died of an overdose on April 23, 2011, less than two days after Conway prescribed him 450 oxycodone pills, prosecutors said.
Christopher Basmas, 29, of Hicksville, died of an overdose on Oct. 27, 2011, within two days of Conway prescribing him 180 oxycodone pills.
Conway's attorney, Richard Langone of Garden City, has said his client always acted in accordance with professional medical standards.
"These youths did not die from the prescribed dosage; they died from ingesting far more than was prescribed," Langone had said earlier this year.
Last November, Dr. Stan Xuhui Li, of Flushing, Queens, was arrested on state charges of criminal sale of a controlled substance and reckless endangerment, after the overdose death of a patient.
But the recklessness charge is a misdemeanor, with a maximum jail term of perhaps a year -- a far less serious charge than the one faced by Conway.
If convicted on the federal charge, Conway could spend decades, if not life, in prison, according to the guidelines of the sentencing commission.