MINNEAPOLIS — A fresh look at an old case. Renewed publicity sparked by a curious blogger. An assault victim with the courage to come forward. And a DNA match in a decades-old crime.

These were just some key factors as authorities worked to solve the Oct. 22, 1989, abduction of Jacob Wetterling, an 11-year-old boy who was kidnapped from a rural road near his home in St. Joseph, about 80 miles northwest of Minneapolis.

On Tuesday, Danny Heinrich, 53, admitted he abducted, sexually assaulted and killed Jacob, burying the body — and Heinrich’s secret — for nearly 27 years. Here are some key elements that unlocked a mystery that had haunted Minnesota for decades:

A new look, and a DNA hit

Jacob was biking with his brother and a friend when he was abducted by Heinrich, who was armed and wearing a mask. His whereabouts were unknown until last week, when Heinrich led authorities to his remains.

Local, state and federal authorities kept Jacob’s abduction a top priority for decades and chased more than 50,000 leads over the years. In 2014, nearly 25 years after the abduction, they agreed to launch what the FBI called a “cold case review” and a new investigator was assigned to the case.

New advances in DNA technology provided the opportunity for authorities to retest some evidence — including a sweatshirt worn by a then-12-year-old boy, Jared Scheierl, who was abducted and sexually assaulted in nearby Cold Spring just nine months before Jacob’s abduction.

The DNA on that sweatshirt was a match to Heinrich, who had provided a hair sample to authorities when he was questioned about Scheierl’s assault in 1990.

“The DNA: That really was the linchpin to propel this investigation forward,” said FBI spokesman Kyle Loven. The positive match set in motion a series of events that culminated Tuesday with Heinrich’s confession.

The search

The DNA match and other evidence gave authorities enough probable cause to search Heinrich’s home in Annandale in July 2015. Instead of items that would tie Heinrich to Jacob, authorities found dozens of images of child pornography, including 19 3-ring binders that contained pictures of naked boys, court documents say.

Stearns County Attorney Janelle Kendall said that after that discovery, authorities began figuring out how they could prosecute Heinrich — and ultimately how they could find Jacob. They couldn’t charge Heinrich with the assault of Scheierl because too much time had passed. And there was no body, so they couldn’t bring a murder charge in Jacob’s case.

Authorities decided to pursue federal child pornography charges, and use the stiff sentence they would carry as leverage to try to get Heinrich to confess.

On the radar

Heinrich had been on authorities’ radar since Jacob’s abduction, Loven said.

Allen Garber, the FBI supervisor on the case at the time, said Heinrich came to authorities’ attention early on, and they put him under surveillance for several weeks.

In 1990, Heinrich was arrested in the assault of Scheierl, but he was released without being charged. And while Heinrich was not charged in other cases, court documents outline multiple sexual assaults of boys in the Paynesville area that are similar to the attacks on Scheierl and Jacob. During a hearing last year, FBI Special Agent Shane Ball testified that Heinrich matched the general description of the suspect in the Paynesville assaults.

In the months before authorities launched their cold case review, a local blogger who calls herself Joy the Curious began doing some research of her own, publishing details about the similarities between the Paynesville attacks, Scheierl’s assault and Jacob’s abduction.

Scheierl, meanwhile, went public with his assault, and also reached out to the Paynesville victims, bringing more attention to the case. The AP typically doesn’t identify victims of sexual assault, but Scheierl has spoken publicly, saying he hoped it could help investigators find his attacker and Jacob’s kidnapper.

Robert Lowery, vice president of the Missing Children’s Division of the National Center for Missing and Exploited Children, said the blogger, Joy Baker, and Scheierl “brought much needed attention to information that was becoming known. And their persistence, I think, caused law enforcement to at least pause and pay attention to what was going on.”

A confession unfolds

Late last month, Heinrich’s attorneys reached out to prosecutors and said they wanted to talk. A flurry of negotiations began, but nothing was guaranteed until Heinrich signed his plea agreement in court Tuesday and publicly admitted what he did.

As part of the deal, which the Wetterling family approved, Heinrich led authorities to Jacob’s remains last week. Last Wednesday, authorities found a portion of the red jacket that Jacob was wearing the day he was abducted. Last Friday, they returned to the area and excavated nearby, where they found Jacob’s bones, teeth and a T-shirt that said “Wetterling.”