A 16-year-old suburban Detroit girl faces up to 20 years in prison in a plot to kill her family members.

The Detroit News and WDIV-TV report that the girl pleaded guilty Monday in Wayne County Circuit Court to assault with intent to murder. She will be sentenced March 28.

The girl's adult boyfriend is serving life for his role in the 2014 plot. Michael Rivera was sentenced in August for attempted murder and conspiracy to commit murder.

Prosecutors say the then-15-year-old girl stabbed her 12-year-old brother in the neck and tried to stab her younger sister in their Plymouth Township home. Police say Rivera guided the girl from outside the house, advising her on what knife to use.