The heartbreaking last words kidnapped Jacob Wetterling, 11, uttered to his killer.

A man has confessed to the murder of an 11-year-old boy who up until this week has been missing for 27 years.

Danny Heinrich from Minnesota admitted to killing Jacob Wetterling as he pleaded guilty to child pornography charges.

Fox9 reported Heinrich has taken a plea deal that will prevent him from being charged with the murder despite his confession.

The 53-year-old is instead expected to be sentenced to a jail term that could see him serve a minimum of five years and a maximum of 20.

It was reported Heinrich saw Wetterling, his younger brother Trevor and their friend Aaron Larson while driving.

The court heard he confronted the boys with a mask on his face and a gun in his hand.

Heinrich said he forced the 11-year-old into the car and handcuffed him to the front seat.

The boy was then said to have turned to his captor to ask: “What did I do wrong?”

Wetterling was said to have been taken to a nearby town where he was assaulted beside a gravel pit in a field.

The 53-year-old said he shot the victim in the back of the head after he heard police sirens.

Wetterling was then dragged to a construction site where Heinrich buried him using a BobCat.

Fox 9 reported Heinrich also admitted to kidnapping and sexually assaulting another boy Jared Scheierl.

Scheierl was able to get free and has since been an advocate for sexual assault victims.

The statute of limitations prevents Heinrich from being charged with the assault of Scheierl.

Stearns County Sheriff John Sanner told the media the plea deal was signed off by members of both affected famililes.

“Any agreement reached or considered was done with full support of Patty and Jerry Wetterling," he said.

A statement released by the Wetterling family was shared on Facebook via the resource centre established in his honour.

"The Wetterlings are deeply grieving and are pulling our family together. We will be eager to talk to media as soon as we are able," the statement read.

Heinrich now faces sentencing for the child pornography charges with both the defense and the prosecution recommending the maximum 20-year sentence.

Feature Image via Facebook/Jacob Wetterline Resource Centre.