An FBI special agent detailed in federal court on Wednesday why Daniel Heinrich has suddenly emerged as the "person of interest" in the disappearance of Jacob Wetterling 26 years ago.

After hearing agent Shane Ball's testimony, U.S. Magistrate Judge Tony Leung ruled that there was sufficient evidence to continue to detain the 52-year-old Annandale, Minn., man on charges of possessing and receiving child pornography.

Leung said Ball's distillation of the evidence "creates quite frankly a chilling context and a gravity of danger to the community."

Ball offered no new information beyond what was contained in 57 pages of court documents released last week, but his focus on several key elements explains why Heinrich has become the prime focus of investigators in the 1989 Wetterling abduction.

Wednesday's session in St. Paul was Heinrich's first court appearance since authorities publicly described him last Thursday as a "person of interest" in the disappearance of Jacob, the 11-year-old boy who was taken by a masked gunman on a rural road, not far from his St. Joseph, Minn., home.

Heinrich is not charged in the Wetterling case.

A short, stocky man with gray thinning hair and glasses, Heinrich sat stoically at the table in a mustard-colored T-shirt and orange jail pants and slippers and said nothing during the 80-minute hearing as Ball ticked off the reasons why Heinrich's home was raided on July 28. Heinrich was arrested Oct. 28 and is currently housed in the Sherburne County jail.

Taking another look

Investigators had looked at Heinrich as a possible suspect in the weeks after Jacob's disappearance.

Ball said Wednesday that authorities focused on him more recently when investigators decided to take another look at the case. "At that point, it wasn't clear to us why … we weren't still looking at him as a suspect," he said.

Ball testified that in the 1980s there were eight incidents of sexual assault of male juveniles involving seven victims in the Paynesville area, near where Heinrich lived. One witness described his assailant as 5 feet, 6 inches to 5-8, "pudgy" and of "heavy build," which Ball said generally fit Heinrich's description.

A hat belonging to the assailant was left at the scene of one assault and has been tested for DNA. The hat contained DNA from several individuals, with results excluding 80.5 percent of the population but not Heinrich, said Ball.

In another incident, Ball testified, a man picked up a juvenile in Cold Spring, drove him around and sexually assaulted him. He was described by the victim as 5-6 to 5-8, with a heavy build and thick nose. That victim, Jared Scheierl, now 39, has come forward. Scheierl was in the courtroom Wednesday.

A composite sketch of the assailant was drawn, said Ball and "there are great similarities between the sketch and Mr. Heinrich."

A sweatshirt belonging to Scheierl was recently found to contain Heinrich's DNA. Ball said it was a match, unlikely to occur with anyone else in the world population. Heinrich could not be charged in that case because the statute of limitations had ran out, authorities said last week.

In the Wetterling abduction, a tire track impression left at the scene corresponded to the tire tread on Heinrich's Ford EXP, Ball said, and a shoe print at the scene had the same tread pattern as Heinrich's shoe.

Both the tire and shoe prints appeared to match, he said, although he acknowledged during cross-examination by public defender Reynaldo Aligada that they were not "exact" matches, which require linking defects in the prints to the shoe and tires.

Child porn charges

The remainder of Ball's testimony outlined a summary of the child pornography charges against Heinrich.

Investigators found 19 three-ring binders containing "numerous images of child pornography" that had been printed from the Internet, Ball said.

Some of the images had the words "Welcome Danny visitor," an apparent reference to the words that appear on the computer screen when Heinrich called up the photos.

Heinrich is also accused of creating "morphed images," in which he superimposed the face of a child, obtained from a 1970 school yearbook, onto a picture of a naked male juvenile. More child pornography images were found on his computer.

When authorities arrived at his house this summer with a search warrant, Ball said that Heinrich told them they would find some child pornography on his computer. He described himself as "a dirty old man" but denied creating the pornography or sharing it with anyone.

Ball said investigators also found more than 100 hours of video of children in the neighborhood. Some of the video focused on their crotches. All of the children were clothed.

On cross-examination, Ball agreed with Aligada that there was no evidence that Heinrich used a video camera to create child pornography. Aligada also pointed out that in a photo lineup in 1989, the Cold Spring victim ranked Heinrich as a less likely suspect than another man. He also underscored that Heinrich voluntarily cooperated with authorities and has repeatedly denied being involved in the assaults.

Leung ended the hearing by saying he may review the issue of detention at a later date. Aligada reserved the right to challenge the detention later.

Afterward, chief federal public defender Katherian Roe, who is co-counsel with Aligada, said defense attorneys would make no comment, and federal prosecutor Steven Schleicher, said he would also not be speaking about the case.

randy.furst@startribune.com 612-673-4224 • Twitter: @randyfurst jenna.ross@startribune.com 612-673-7168 • Twitter: @byjenna pam.louwagie@startribune.com 612-673-7102 • Twitter: @pamlouwagie