Jacob Wetterling’s killer was finally willing to talk — a break authorities attributed to an unconventional legal strategy that didn’t end with a murder charge but appeared to provide some closure.

Law enforcement officials close to the case sat stone silent in federal court Tuesday, waiting for a confirmation that would finally explain what happened to Jacob Wetterling.

Minutes after entering the Minneapolis courtroom, Danny Heinrich signed off on a plea agreement to a single federal child pornography charge, ending 10 days of uncertainty that included the discovery of Jacob’s remains and a confession by Heinrich of what he did to the 11-year-old boy that night in October 1989.

“We didn’t know if we would ever get here,” U.S. Attorney Andrew Luger said after Heinrich’s hourlong plea hearing that explicitly detailed the night of Wetterling’s murder and steps he took to hide the boy’s body.

While authorities say that Heinrich, 53, could spend the rest of his life in custody, the resolution to Jacob’s disappearance happened without a murder charge being filed.

Beyond convincing Heinrich to cooperate, the break in the case required involvement from numerous law enforcement agencies, benefited from advancements in forensic technology and needed the blessing of Jacob’s family.

In a nine-page document, and before Chief Judge John Tunheim in court, Heinrich agreed that both his attorneys and federal prosecutors would ask for the maximum 20 years in federal prison for the child pornography charge when he is sentenced on Nov. 21. Upon his release, Heinrich will be subject to evaluation to be placed in either state or federal civil commitment.

Jacob’s murder, and the January 1989 abduction and sexual assault of Jared Scheierl, were included in the document as “relevant conduct” that called for the maximum sentence in the child pornography case.

Authorities named Heinrich a person of interest in Jacob’s disappearance when they announced his arrest on what eventually became 25 counts of federal child porn charges, which carry much more severe penalties than similar charges in state court. From the beginning, Luger said, prosecutors made clear to Heinrich that they wanted to discuss the Wetterling case: Any plea deal would need to end in a long prison sentence and an answer to what happened to Jacob.

Stearns County Attorney Janelle Kendall called Luger after investigators searched Heinrich’s Annandale home last July, finding binders full of child pornography, a computer with more evidence and children’s clothing. A federal prosecution for child pornography could help uncover the truth behind Jacob’s disappearance, Luger said she told him.

At the news conference Tuesday, Kendall said finding Jacob was the point of that investigation. But with no body, the state could not charge Heinrich, or anyone with Wetterling’s murder, she said. Proof that Jacob was killed still did not exist until last Friday, after Heinrich led investigators to a grave in rural Paynesville. But it was the federal child porn case that helped apply pressure that made Heinrich talk.

The statute of limitations had expired in both Scheierl’s case and a series of sexual assaults around Paynesville. But a DNA hit last year linking Heinrich to Scheierl’s assault “triggered a series of carefully planned, thought-out events,” said Stearns County Sheriff John Sanner.

“Despite the complications of this path,” Kendall said, “this case demonstrates that no case is too hard to solve, no tip too insignificant to consider, and no legal obstacle insurmountable in finding answers and accountability for Jacob Wetterling and for everyone near and far who knows his name.”

Adding a state murder prosecution might have given more time for a “volatile and unpredictable” Heinrich to change his mind, Luger said, adding that “this was not an opportunity that we could pass up.”

The first sign the strategy would pay off came in late August, when Heinrich’s attorneys said he was willing to cooperate.

Both sides began drafting a tentative agreement on Aug. 26, stipulating that Heinrich must lead authorities to Jacob’s remains and provide a full, detailed confession to what he did to Jacob and to attacking Scheierl earlier that year.

The plea document describes the deal as a “global resolution” to the federal child porn prosecution, Scheierl’s assault and one of the state’s most wrenching mysteries.

Last Wednesday afternoon, Heinrich accompanied investigators to the site, where Jacob’s red jacket was found. The boy’s teeth, bones and a T-shirt bearing his name were discovered after another extensive search two days later.

Luger called the 10 days leading to Heinrich’s admission the most “difficult for us professionally in our lives” and said it required confidence from the Wetterling family.

Though not charged with murder, Luger said, Heinrich “is not getting away with anything.”

“We got the truth,” he said. “The Wetterling family can bring [Jacob] home.”