"He told them after killing her, he placed her remains in three separate garbage bags," Beckett said.

He said Christensen told his attorneys that he tossed the bags into a dumpster near his apartment before he disposed of her clothes, cellphone and other of her personal items in dumpsters around the area, which is about 120 miles (195 kilometers) southwest of Chicago.

Sanitation workers emptied the dumpster that purportedly contained the victim's remains a few days later and took the contents to a landfill in the Danville area, where they were compacted "at least twice" before being taken to a private landfill and covered with least 30 feet (9 meters) of trash.

He said that although authorities have a general idea of where the remains might be, recovering them would be expensive and difficult.

Such an effort would also be complicated by environmental rules regarding digging at landfills and the fact that the remains have certainly decomposed and are believed to be "very small in size."

Beckett also pointed out that there is no way to determine if Christensen told the truth about what he did with Zhang's body.

He said Christensen told his attorneys what he did with the remains last November and the attorneys discussed offering to give the information to prosecutors in exchange for their agreement not to seek the death penalty.

However, although prosecutors considered such a plea bargain, they decided against it after determining there was no way of knowing if Christensen was telling the truth and if the body could never be found.

Beckett also said the defense attorneys had to know that by making that information public, which the Zhang family desperately wanted, would have alerted jurors deciding whether to spare Christensen's life that he not only had decapitated her, he had also dismembered her.

"The defense did not want the information about what he did with the body put before the jury. ... Treating this young woman as leftover vegetables and throwing her out with the garbage," Beckett said.

The Zhang family's attorney from China said he understood the decision by prosecutors not to accept Christensen's word about what happened without any proof.

"Christensen has lied so many times," said Wang Zhidong. "... We don't believe his attorneys have any reason to lie, but at the same time, no one can say what Christensen told his attorneys is true."

Zhang Ronggao, though, said he was disappointed that prosecutors waited so long to tell his family what Christensen had said.

The US attorney's office that prosecuted Christensen declined to comment.

Zhang Ronggao said he hopes a memorial to his daughter that would include the burial of her clothing could be built somewhere on campus.

As for Christensen, whom he had begged to "end our torment" by revealing what he did with the body after the trial, the heartbroken father said this: "We hope that he suffers for the rest of his life, as he made Yingying suffer in the last moments of her life."

AP