A review of 31 cases shows more than half of officers involved had fewer than two hours of training past five years.
He was convicted of sexually assaulting four boys around the time Jacob was abducted.
He was detained in connection with the 2012 shooting of a Cold Spring police officer, but later declared not a suspect.
He is convinced the Stearns County Sheriff's Office hasn't looked hard enough for his son, who disappeared 14 years ago.
The woman Patty Wetterling didn't want to see.
Just days after the shotgun killings of Alice Huling and three of her children, he was interviewed by Stearns County sheriff's deputies and then let go.
The number of people on the nation's sex-offender registries has exploded to hundreds of thousands. But researchers question the registries' effectiveness, note their inconsistencies and suggest they might be doing more harm than good. Even Patty Wetterling has changed her views.
They don't happen often, but when they do, child abductions by strangers can capture Americans' attention like few other crimes. A look at notorious kidnappings over the past century and a half shows how attitudes have changed.
The police twice used the label "person of interest" in the Wetterling case. It's an imprecise term that stops short of calling someone a suspect but can leave a person in a long-term limbo.
Years after the abduction, when he finally told the police of his actions that night, investigators took a different tack.
He turned the focus of the Wetterling investigation to Dan Rassier, only to have one of the first suspects in the case, Danny Heinrich, confess.
They can rule out a suspect, but shoe prints and tire tracks in the dirt lack solid standards for use as forensic evidence.
Investigators in Jacob Wetterling's disappearance used lie detectors "a lot," one of them says. But some research suggests they're not much more reliable than flipping a coin.
Wetterling investigators used hypnosis to prod memories, but some experts fear the process can cause people to remember things that didn't happen. So while it may help investigations, courts have been wary to accept it as evidence.
'What was done was what we could do'
Early on, investigators circulated a number of police sketches, hoping they would generate better leads in Jacob Wetterling's abduction. But sketches can be tricky and lead potential witnesses down the wrong path.
Abducted months before Jacob, he tried for years to find his kidnapper.
DNA profiling has grown up since the Wetterling abduction, becoming both more powerful and, sometimes, as much art as science. It played an important role in shaping the case against the man who led authorities to Jacob's remains.
More than anyone else, she has been the face and voice of the search for Jacob.
He called 911, then gradually was pulled into massive investigation.
Long known to investigators looking into the Wetterling abduction, he originally denied connection to the case but now admits that he murdered Jacob and pointed authorities to his remains.
Nothing frustrated him more than not solving the Jacob Wetterling abduction.
His kidnapping on Oct. 22, 1989, became a national spectacle and led to a 27-year investigation.
More reserved than his wife, Jacob's father struggled with the investigation and turned to psychics.