Pedro Martin pleaded not guilty earlier this week to the murder of 20-year-old Megan Marotte.
But police say that in a videotaped confession, he admitted to strangling Marotte when she asked for more money to have sex with him.
The victim's body was found in Willowbrook Park last Thursday, nearly two weeks after she was reported missing.
A person walking their dog smelled a foul odor and called police. There were no obvious signs of trauma.
Relatives say Marotte had struggled with drugs and was living with her brother ever since her father's death in 2011, and that they were concerned about her safety.
Marotte was last seen August 4, just up the street from Martin's apartment.
Marotte used to play with Virginia DiBella's granddaughter when the kids were little. She says that is not the person she remembers.
"Around Halloween, we used to fill up bags with leaves, and she was here playing," DiBella said, "Always mannerly, always wonderful, always gave you the time of day and respect."