Authorities found Autumn Pasquale's body Monday night while acting on a tip from the boys' mother, who was alarmed by something she read on one of their Facebook pages, authorities said.
The arrests came Tuesday after police searched the boys' home and found the bike the girl had been riding and other possessions she had with her when she disappeared over the weekend.
In their first interview since Autumn's body was found in a bin next to the boys' home, her parents, Jennifer Cornwell and Anthony Pasquale, talked about how strong their daughter was and the horrible ending to her life.
"She was a tough girl, a tough cookie," Cornwell said, saying she did not deserve to be treated "like a piece of trash."
Pasquale said he knew the family of the boys arrested in the death.
"Everybody knows everybody," in the town of 8,000, he said, "whether they're friends or acquaintances."
The parents said they had been overwhelmed by the support from the community and the donations they have received, and knew their daughter would want them to stay strong.
Funeral services were set for 2 p.m. Saturday at Our Lady of Lourdes Church in Glassboro, following a public viewing set to start at 8 a.m.
Because the brothers, who are 15 and 17, were charged as juveniles, authorities have not made their names public. They are expected in court for a detention hearing Friday.
Gloucester County Prosecutor Sean Dalton said it's likely he'll ask that the case be moved to adult court, where all the proceedings would be public.
A public defender believed to have been assigned one of the defendants was not in the office and unavailable for comment Wednesday afternoon.
The teens turned themselves in Tuesday and were charged with first-degree murder, conspiracy to commit murder, disposing of a body, tampering with evidence and theft. The younger boy also was charged with luring.
Dalton said the 15-year-old persuaded the biking-obsessed Autumn to come to his home so they could trade BMX bike parts, and that the brothers stole her prized bike. But he would not discuss a possible motive for the killing.
The boys' father, who said he was divorced seven years ago from their mother, told WPVI-TV in Philadelphia he hadn't seen the boys in a year, had a sleepless night after hearing about the girl's killing and the charges against "my two little sons."
The boys' mother recently remarried.