Morristown, N.J. — A Massachusetts woman who plotted with her boyfriend to gun down the man's wife as the couple was walking with their toddler son on a New Jersey street four years ago has been sentenced to 30 years in prison.

Friday's sentencing was part of a plea agreement in which 30-year-old Antoinette Stephen of Billerica pleaded guilty to murder and testified against the boyfriend, 29-year-old Kashif Parvaiz of New York City.

Parvaiz was found guilty of murder and other charges and was sentenced last month to life in prison plus 10 years.

The August 2011 shooting occurred while Parvaiz and 27-year-old Nazish Noorani walked with their young son in Boonton, a suburb about 25 miles west of New York City. Stephen was having an affair with Parvaiz and admitted firing the fatal shots. The boy was not hit by gunfire.

Stephen said she used two guns to kill Noorani, and wound Parvaiz to try to make the shooting look like a bias attack or robbery. She said she was following Parvaiz's orders.

Parvaiz told authorities after the shooting that the couple had been attacked by a group of males shouting the word "terrorists."

Stephen will be ineligible for parole for her entire 30-year sentence.