Wichita ? For decades since the strangulation deaths of his parents and two younger siblings, Charlie Otero futilely has sought answers to why his family was murdered.

Now, 31 years after their deaths, Otero and other family members of the BTK killer’s 10 victims will have to wait longer for answers.

The man charged in the BTK serial killings waived his right to a preliminary hearing Tuesday, an acknowledgment that the state has enough evidence to go to trial. That means prosecutors will not have to publicly reveal any of their case against Dennis Rader until trial.

Rader, formerly a city ordinance enforcement officer for suburban Park City, was arrested Feb. 25 and is charged with 10 counts of first-degree murder. Rader, 60, will enter a plea at his arraignment, set for May 3.

Otero said in a phone interview from his home in Albuquerque, N.M., that he was “extremely disappointed” that he would have to wait to hear the evidence in the case.

On Jan. 15, 1974, the three surviving children of Joseph and Julie Otero came home from school to find their parents and two other siblings, Josephine, 11, and Joseph II, 9, dead at the family’s Wichita home.

Otero said he was anticipating one day testifying against Rader.

“I am looking forward to seeing him face to face,” said Otero, who was 15 when he found his parents’ bound bodies in their bedroom in 1974. Police told him later that his brother and sister also were killed.

The strangulation of Otero’s four family members were the earliest deaths claimed by the killer who nicknamed himself BTK, for “Bind, Torture, Kill.”

Dennis Rader, left, accused in the BTK serial killings, talks with his attorney Sarah McKinnon after waiving his preliminary hearing Tuesday in the Sedgwick County Courthouse in Wichita.

The BTK strangler had been suspected of eight torture deaths beginning in 1974, but since Rader’s arrest authorities have linked two more victims to the serial killer. Prosecutors can’t seek the death penalty because the crimes were committed before 1994, when Kansas passed its capital punishment law.

Prosecutors presented no evidence Tuesday against Rader, who was neatly dressed in a gray suit and wearing leg restraints. In a preliminary hearing, prosecutors need only to prove that they have enough evidence to show probable cause that a crime was committed and that the defendant did it.

“Considering the low burden of proof, we didn’t think there would be anything new that would come out anyway, so we didn’t think there was much to be gained by having a preliminary hearing,” Rader’s attorney Steve Osburn said after the brief hearing.

Dist. Atty. Nola Foulston told reporters: “Of course there is a certain type of disappointment because it prolongs the agony for the public to know. And as long as the public doesn’t know, it places us in a position where we are out here telling you, ‘I’m sorry, I can’t tell you.”‘

Osburn said after the hearing that Rader, who is cooperating with his attorneys, would plead not guilty and request a jury trial at his arraignment. An arraignment is normally held right after a preliminary hearing, but Osburn said he asked it be continued to give the defense more time to prepare.

Tuesday in Topeka, Gov. Kathleen Sebelius proposed adding nearly $405,000 to the state budget to cover costs associated with Rader’s defense.