How DNA led to arrest in cold-case killing of Indiana 8-year-old after it 'haunted the community for 30 years': Prosecutor April Tinsley, 8, was raped and killed in April 1998.

DNA and genetic genealogy led to the arrest this week of an Indiana man accused of killing a little girl in 1988, appearing to bring some closure to a mysterious cold case that "haunted the community for 30 years," Allen County Prosecutor Karen Richards said Tuesday.

John Miller, 59, was arrested Sunday in the killing of 8-year-old April Tinsley, who died in Indiana in April 1988, the Allen County Prosecutor’s Office said.

"Thirty years this family has waited for answers," Fort Wayne Police Chief Steve Reed said as local, state and federal officials gathered at a news conference Tuesday, praising all those who poured their energy into the case over three decades.

"From the Indiana State Police to the family of April Tinsley, we hope and we pray that this brings you some measure of closure and some measure of peace that you’ve been seeking for the last three decades," Indiana State Police Sgt. Ron Galaviz said. "I know somewhere up there there’s a little girl dancing with her angels. She’s celebrating. So when you get on your knees tonight and you talk to her in your dreams and prayers tell her, 'They did it. They did it and we got him.'"

Galaviz added, "We would not be here today, 30 years down the road, if it was not for the hard, tireless dedication of the initial investigators" who preserved information that will now be evidence in the case.

One of those investigators is now-retired Fort Wayne Det. Dan Camp, who told ABC Fort Wayne affiliate WPTA-TV he is "elated" by the arrest "after 30 long exhaustive years."

The profile they had made of April's likely killer "hit it right on the head to what John Miller looks like and his characteristics today," he said.

"I think about April often. I carried her picture in my wallet for a long, long time," Camp told WPTA-TV, adding that he hopes to attend each day of Miller's trial.

The cold case began April 1, 1988, when April was reported missing. Her body was found in a ditch three days later, according to the probable cause affidavit. She died of asphyxiation with indications of sexual assault, according to the court document. DNA was recovered from her underwear.

In 1990, officers found writing on a local barn from the suspected killer, saying, "I kill 8 year old April M Tinsley did you find her other shoe haha I will kill agin [sic]," according to the court document.

Years passed, and in 2004, officers found notes from April's suspected killer and used condoms at three locations in the Fort Wayne area; the notes said the person who "left the condoms had raped and killed April," according to the court document.

DNA from the abandoned condoms was consistent with the DNA recovered from April's underwear, the probable cause affidavit said.

Police pursued genetic DNA testing this year in the decades-old cold case and, in July, the DNA was narrowed to two brothers, including Miller, the documents said.

Police conducted surveillance and collected trash, including three used condoms from Miller, according to the probable cause affidavit.

DNA from the condoms was consistent with the condoms recovered in 2004 as well as the DNA from the crime scene, the probable cause affidavit said.

Police went to Miller's home Sunday and he agreed to go to the Fort Wayne Police Department, where he was advised of his rights and agreed to talk to detectives, the documents said.

When detectives asked Miller whether he knew why the police wanted to talk to him, he allegedly replied, "April Tinsley," the probable cause affidavit said.

Miller allegedly admitted to abducting April, raping her and choking her to death, saying it took about 10 minutes for her to die, the probable cause affidavit said.

Miller was preliminarily charged with murder, child molesting and confinement, the prosecutor’s office said. Formal charges will be filed when he appears in court July 19, prosecutors said.

"When they told me that he confessed to this crime, my brother died [to me]," Miller's brother, who was not named, told WPTA-TV. "I'm done. I mean it's sad to say that but … what he did is just sick. ... I have no intention of talking to him."

The brother described Miller, who previously worked at Walmart, as “fairly quiet,” adding, “he's got a temper -- a real short fuse.”

“Whatever he gets he deserves,” he told WPTA-TV. “I just wish he would've got caught a long time ago.”

ABC News' Brian Hartman contributed to this report.