Johnson County Attorney Phill Kline said the grand jury indictment replaces charges previously filed by Kline's office.
Hall, 26, of Olathe, is accused of kidnapping Smith on June 2 from the parking lot of a Target store in the Kansas City suburb of Overland Park. Grainy surveillance video from the store showed Smith being confronted and pushed into her car.
Her body was found four days later in a park about 20 miles away in Missouri. Hall was interviewed and arrested the same day, June 6, after he saw himself on television in surveillance video and contacted a lawyer, who contacted police.
The indictment announced Tuesday night makes a preliminary hearing — where evidence in the case would have been presented to determine whether a trial was warranted — unnecessary. Kline said if there been a preliminary hearing, the public would have been privy to evidence before the case got to trial.
Hall's lawyer, Paul D. Cramm, did not immediately return calls seeking comment about the indictment Wednesday. So far, Cramm has not commented publicly because of a gag order issued in the case.
Peter A. Joy, professor of law at Washington University in St. Louis, said Wednesday that during a grand jury proceeding, the "burden on the prosecutor is very minimal." He said there are there are no rules of evidence that have to be followed and there is no cross-examination by the defense.
"The things we take for granted in our judicial process — the transparency and that the accused has some representation and the ability to test the witnesses — are missing in grand jury proceedings."
"The grand jury process is private and secret and the evidence not provided in a public fashion," Kline said during a news conference Tuesday night.
Kline declined to comment afterward about whether he had pushed for the indictment, saying he couldn't discuss strategy.
He said the grand jury process helps preserve a fair trial by not revealing evidence, and it also protects the privacy rights of the victim's family.
At the news conference, Smith's parents, Greg and Missey Smith, thanked Kline for his "support for the privacy of our family, honoring Kelsey's memory and ensuring that the trial proceeds fairly."
Hall's arraignment is scheduled for 1:30 p.m. Wednesday. After that proceeding, Kline will have five days to decide whether to pursue the death penalty.