The sister-in-law of Kermit Gosnell - the West Philadelphia abortion doctor serving life for murdering three infants born alive during abortions - was sentenced Tuesday to a year's probation for lying to a county grand jury investigating the 2009 overdose death of an abortion patient.

Philadelphia Common Pleas Court Judge Benjamin Lerner praised Elizabeth Hampton's decision to plead guilty and testify against Gosnell, whom Lerner called a "charismatic sociopath."

In a related development Tuesday, federal prosecutors filed notice that Gosnell, 72, would plead guilty June 6 to drug charges involving the sale of prescriptions for dangerous narcotics.

It was the drug probe that resulted in the Feb. 18, 2010, raid of Gosnell's clinic that revealed evidence he was performing illegal late-term abortions.

In sentencing Hampton, Lerner called her "the least culpable" of nine clinic workers charged with Gosnell in the operation of the Women's Medical Society at 3801 Lancaster Ave. Unlike the others, Hampton did not assist Gosnell in abortions, Lerner said.

Struggling to control her emotions, Hampton, 55, asked for "forgiveness for what I've done wrong." She also thanked her lawyer, Murray Dolfman, and Assistant District Attorney Joanne Pescatore "for being in my corner."

Pescatore told Lerner that Hampton had had a complete turnaround since she lied before the grand jury in 2010.

"She was very scared of Dr. Gosnell and she lives in a house he owns," Pescatore said.

Hampton is the "foster sister" of Gosnell's third wife, Pearl Gosnell, and at trial described how she was bound to Gosnell by finances and family ties.

At trial, Hampton testified about a 2002 incident that caused her to quit the clinic for several years, a time when she slipped into alcoholism.

On Tuesday, Pescatore revealed what the jury never heard: Hampton saw Gosnell killing a baby born alive by snipping its spine with scissors.

Because Hampton told prosecutors about the incident for the first time while being prepped for trial, Pescatore said prosecutors were not permitted to use the detail.

Hampton was charged with lying to the county grand jury about the Nov. 19, 2009, death of abortion patient Karnamaya Mongar, 41, of Virginia. Mongar went into cardiac arrest after Gosnell's untrained staff gave her too much Demerol.

Hampton is the first of nine Gosnell employees to be sentenced. Gosnell's wife and two other workers will be sentenced Wednesday by Lerner.

Contact Joseph A. Slobodzian at 215-854-2985, jslobodzian@phillynews.com, or @joeslobo on Twitter.