To crack Minnesota's biggest cold case — the 1989 abduction of 11-year-old Jacob Wetterling — authorities went back to the early days of the investigation.

They turned a renewed spotlight last year on a man who was questioned soon after Jacob's disappearance but was never charged. That ultimately led to Saturday's announcement that Jacob's remains finally had been found.

"On these kinds of cases it's really a tribute to law enforcement that they simply never give up. ... This is what persistence will reveal," Michael Campion, former superintendent of the Minnesota Bureau of Criminal Apprehension and former commissioner of the state Department of Public Safety, said Sunday.

The case has not lain dormant for those 27 years, said Tom Heffelfinger, former U.S. attorney for Minnesota. To the contrary, he said, it's been a top priority for local and federal law enforcement the entire time.

When authorities last October announced the arrest of Danny Heinrich, now 53, of Annandale, on child pornography charges, they took the unusual step of calling him a "person of interest" in the Wetterling case, though they were careful to stop short of calling him a suspect. He has not been charged in Jacob's abduction and death.

Jacob was riding his bicycle near his home in the central Minnesota community of St. Joseph with his brother and a friend on Oct. 22, 1989, when a masked gunman abducted him and ordered the other boys to run. The case has haunted Minnesota ever since. Jacob's smiling face was burned into the state's collective psyche, appearing on countless posters and billboards seeking clues.

Jacob's mother, Patty Wetterling, became a nationally recognized advocate for the cause of missing and exploited children. A 1994 federal law named for Jacob requires states to establish sex offender registries.

As part of the fresh look into Jacob's abduction around its 25th anniversary, investigators took another look at the sexual assault of a 12-year-old boy from Cold Spring nine months before Jacob's disappearance. Investigators had long suspected the two cases were connected.

Heinrich was arrested in 1990 in the sexual assault case but wasn't charged due to a lack of evidence. While he was questioned extensively about Jacob's kidnapping at the time, he denied any involvement.

Using technology that wasn't available back in 1989, investigators found Heinrich's DNA on the 12-year-old's sweatshirt, Richard Thornton, special agent in charge of the FBI's Minneapolis office, said when authorities announced Heinrich's arrest last October. They used that evidence to get a search warrant for Heinrich's home.

While they didn't discover anything to firmly tie Heinrich to either Jacob's kidnapping or the assault on the other boy, they found a large collection of child pornography. Heinrich was charged with 25 child pornography counts.

At the time of his arrest last year, as he had done since 1989, Heinrich insisted he was innocent in Jacob's disappearance.

Heinrich, who has been jailed since his arrest, pleaded not guilty to the child pornography charges and is scheduled to go on trial on those counts in October.

A law enforcement official told The Associated Press on Saturday that a person of interest in Jacob's abduction took authorities to a field in central Minnesota the week before. The official, who spoke on condition of anonymity because of the ongoing case, said buried remains and other evidence were recovered.

"Once they realized they had a strong, legitimate case against Mr. Heinrich for other crimes, in this case child pornography, they aggressively prosecuted him for anything and everything they could get," Heffelfinger said.

The Stearns County Sheriff's Office released few details over the weekend about the new developments in the Wetterling case, and no fresh information Sunday, but said that authorities expect to be able to provide more details early this week.

Campion said he spent only a little time on the Wetterling investigation in 1989 but was still "at a loss for words" on Sunday, still processing the break in one of Minnesota's most enduring mysteries.

"I don't know that I ever thought I'd see that in the headlines," he said. "It's pretty astonishing."