Tammy Pitts Gaddy, 41, was stabbed and her daughter, Natassia, strangled, NJ.com reported. Gaddy's body was on the first floor and Natassia's in the basement.
Bergen County Prosecutor John Molinelli said investigators believe Gaddy knew her killer.
Neighbor Vaun Sims told NJ.com Natassia's father was still hospitalized after a stroke. He said the father did not live with Gaddy.
"She was a sweet person -- a very, very good mother," Sims said.
Police Chief Arthur O'Keefe said officers went to the apartment after a neighbor reported a possible burglary. They found several people inside who said they had come over because they had not heard from Gaddy and were worried about her.