(CBS/AP) DES MOINES, Iowa - The body of Kathlynn Shepard, a 15-year-old Iowa girl who was abducted last month along with a younger friend after getting off a school bus, was found in the Des Moines River, authorities said Sunday.
An autopsy confirmed the body found Friday night under a bridge near Boone is that of Shepard. Her kidnapping on May 20 in the small city of Dayton led to a massive search involving federal, state and local authorities.
Chief State Medical Examiner Dr. Julia Goodin said Sunday that Kathlynn's death was a homicide and that she died of "multiple sharp and blunt force injuries." The autopsy was completed a day earlier.
Residents of Dayton, about 60 miles north of Des Moines, had braced for the news. Investigators had expressed confidence the body -- concealed by debris when discovered by a fisherman -- was Kathlynn's. Clothes on it matched what the high school freshman was wearing when a man lured her and a 12-year-old friend into a pickup truck.
Authorities also found zip ties matching ones used to restrain the younger girl, who managed to escape and call 911.
"Today our family has lost part of its soul -- not just the Shepard family but the families of Dayton and all of Iowa," the Shepards said in a statement. "An innocent, caring, fun-loving child was taken from this world long before her time."
Authorities said Kathlynn and her friend were lured into a pickup that police believe was driven by registered sex offender Michael Klunder. They said Klunder took the girls to a hog confinement facility where he worked, and the 12-year-old girl was able to get away.
Klunder, 42, was found dead hours later at another rural property. Authorities said he hanged himself.
Gerard Meyers, assistant director of field operators for the Iowa Division of Criminal Investigation, said Sunday that authorities believe Klunder acted alone.
"We have no indications of any co-conspirators," he said.
Meyers has said a positive identification would be "the final trigger for not only the family but the community, our investigative personnel, our partner agencies ... to move into that next phase, which is really the closure phase of this very unfortunate circumstance."
Hundreds of officers and volunteers had searched for Kathlynn, but hopes of finding her alive were dampened when testing confirmed that blood found on Klunder's truck and at the hog building was Kathlynn's.
"We were robbed of some innocence in this whole thing," said Webster County Sheriff James Stubbs after the body was discovered. "We'll never quite be the same. Hopefully time will heal some of those wounds, but the awareness is a lot higher than it was before."
Klunder had been released from prison in 2011, after serving 20 years for convictions in two separate Iowa kidnappings that occurred on back-to-back days in December 1991.
Police also are investigating whether Klunder is responsible for kidnapping and slaying of Lyric Cook and Elizabeth Collins, two young cousins who vanished while riding bikes in Evansdale, about 90 miles from Dayton. The bodies of the girls, who were ages 10 and 8 when they vanished, were found in December in a wooded area in Bremer County, where Klunder once lived in a home for emotionally troubled youth.