On Tuesday, a state police spokeswoman said a DNA analysis by the Virginia Medical Examiner's Office determined that the remains were those of Kidwell.
Three Capon Bridge, W.Va., residents, Ryan Nenigar, 20, and 24-year-old twins Stephen Cooper and Scott Cooper, previously were indicted by a Hampshire County grand jury in connection with Kidwell's death, Gall said.
Nenigar, who is Kidwell's former boyfriend, was charged with premeditated murder, and Stephen Cooper and Scott Cooper each were charged with conspiracy to commit murder.
Gall declined to go into detail Wednesday about the cause of Kidwell's death or a motive.
Gall said he did not want to comment about the motive before the three defendants, who were being held at the Potomac Highlands Regional Jail in Augusta, W.Va., face trial in Hampshire County Circuit Court. A trial date has not been set.
"We've got some theories," Gall said.
Gall said he believes Kidwell was killed in the area of Dillion's Run Road, near the Hampshire County community of Capon Bridge. The defendants live in the Dillion's Run Road area, Gall said.
It is believed that after Kidwell was killed, she was taken by automobile to Virginia and her body dumped into Back Creek, upstream from Gore, Gall said.
Smith said she was not sure how Kidwell and Nenigar met, but she said they dated for about two years.
For most of Kidwell's family members, her disappearance came as a surprise, said Smith, of Paw Paw.
Smith said she wanted to thank all the area volunteer firefighters and police who have helped search for Kidwell over the last year. Not knowing Kidwell's whereabouts has been stressful for the family, Smith said.
Family members were notified about the charges against the defendants last Christmas Eve and they were notified about the results of the DNA analysis on Father's Day, Smith said.
"It's been a very long year," she said.
Because Kidwell did not have any life insurance, a fund has been set up to collect donations to help pay for her funeral and other expenses, Smith said.
Checks can be made out to the Christa Kidwell Memorial Fund and sent to the Bank of Romney, P.O. Box 114, Paw Paw, WV 25434.