A northern New Jersey mom accused of fatally beating her 4-month-old son because the child would not stop crying has pleaded not guilty to aggravated manslaughter.

Karen Stewart of Prospect Park also pleaded not guilty to aggravated assault and child endangerment charges during a court hearing on Wednesday. She remains jailed on $350,000 cash bail.

Authorities say the beating occurred March 24.

Passaic County prosecutors added the aggravated manslaughter charge Monday after reviewing the results of the boy's autopsy, which determined the death was a homicide.

The 21-year-old Stewart faces up to 50 years in prison if convicted on all three counts.


Copyright 2013 The Associated Press.