30-year-old Alex Jeffrey is facing murder charges.
It's not known why the Bedford-Stuyvesant man allegedly killed her.
Neighbors described Merceda Young as a hardworking single mom who focused on her teenaged son and pre-teen daughter.
The 35-year-old was found dead underneath a blanket Tuesday near Kent and Division Avenues in Williamsburg.
She was stabbed several times in the neck.
"I'm devastated. She was so close to me and I didn't even know. I feel real bad. It's such a tragedy," said Kevin Hugget, a neighbor.
Neighbors say young lived on Chatterson Avenue in the Bronx for seven years.
They say she was heavily involved in her community including working with the YWCA.
The organization said, "We are saddened to learn of the brutal murder of Merceda Young. Our hearts go out to her family and friends during this difficult time."
What long time neighbors just can't understand is how such a peaceful person could wind up murdered.
"We were wondering how this happened because she's a good person," said Lina Khalid, a neighbor, "She never stand outside. She don't talk to people like that. She's a good person. She never gave any problems."
Neighbors say Young's children are now with their father.