Jenni-Lyn Watson Update: Ex-Boyfriend Charged with Murder of Dance Student in Upstate N.Y.

CLAY, N.Y. (CBS/WTVH/AP) Jenni-Lyn Watson, the 20-year-old dance student who vanished last week while on Thanksgiving break in her hometown in upstate N.Y., was killed by her on-again, off-again boyfriend, who then dumped her body in a park "like garbage," a prosecutor said Saturday.

PICTURES: Jenni-Lyn Watson Missing

Onondaga County District Attorney William Fitzpatrick said 21-year-old Steven Pieper of Liverpool, N.Y., was charged with murder in Watson's death.

Pieper pleaded not guilty Saturday night at his initial appearance in Clay town court.

Pieper was held without bail because of the seriousness of the charge, Fitzpatrick told the Syracuse Post-Standard.

Eden Mishler, a dance major who met Watson three years ago during her freshman year at Mercyhurst College in Erie, Pa., told The Associated Press that she had met Pieper several times but didn't know him that well.

"She would talk to us, just saying, after they broke up, that he was trying to contact her and friend request her on Facebook," the 21-year-old Mishler said. "She was avoiding him."

But she said the two had a rocky relationship, and there was some jealousy. Nevertheless, Mishler thought he cared for her.

Piper and Watson had dated on and off for 18 months, according to Fitzpatrick, and she wanted to the relationship to end but "that message apparently did not get through," reports CBS affiliate WTVH.

The arrest came hours after searchers combing through woods for any sign of Watson found the body of a woman believed to be the missing student covered in debris behind a storage shed in a swampy area of Clay Central Park, Fitzpatrick said.

The site was part of a 1,200-acre area canvassed by more than 100 police and volunteers in suburban Syracuse.

Fitzpatrick said Pieper was upset when Watson tried to end their relationship in early October. He said investigators believe Pieper killed Watson at her parents' house on Nov. 19, and her body was "dumped, frankly, like garbage," in the park.

"We do not believe she left that house alive," Fitzpatrick said.

COMPLETE COVERAGE OF JENNI-LYN WATSON ON CRIMESIDER