Police found an immaculate home when they entered Daniel Acker's off-white, two-story Waukesha condo this week to investigate allegations about the suspected pedophile.
He had hidden his darker secrets in the basement.
Lifting the roof off of a model police station, investigators found a dozen photos of children who had been abducted and murdered pasted to the small walls.
"It's bizarre. No one in this agency has seen anything like it before," said Greenfield police Deputy Inspector Bradley Wentlandt, whose department is leading an investigation into allegations that Acker molested a number of young boys dating back to the 1970s.
The investigators found evidence that Acker had a keen interest in murdered boys, although he has not been linked to any deaths.
"His basement contained many of the things you would expect to see in a pedophile's basement, toys, games - things children would play with - for a man who doesn't have any children," Wentlandt said.
Acker, 61, was arrested Monday while coaching youth swimmers at Frank Lloyd Wright Middle School in West Allis, where he was about to give a swim lesson. A man in his 40s had told police that day that Acker sexually assaulted him from 1971 to 1976, when he was from 11 to 15 years old.
Since then, at least three other men in their 40s - including one who lives in Tennessee - and a 19-year-old man have told police they had been sexually assaulted by Acker when they were minors, Wentlandt said.
"We believe we've only scratched the surface in people we've talked to already. We believe there are more victims out there," he said.
Scores of people called Greenfield police Friday after details of the allegations were announced. The FBI and the U.S. attorney's office are reviewing the case, as are state child welfare officials, because Acker was a foster parent as recently as 2006.
Acker, who is being held in the Milwaukee County Jail, was charged Friday with second-degree sexual assault of a child involving the 19-year-old.
If convicted, Acker faces up to 40 years in prison and a $10,000 fine. He is expected to appear in court Saturday.
According to a criminal complaint:
The victim told police Acker was his swimming instructor in 2005. Around August of that year, when he was 15, the boy went to Acker's West Allis home in the 7700 block of W. Rogers St.
Acker admitted to a detective that he gave the boy a massage and had sexual contact with him several times, the complaint says.
Other men have told police Acker assaulted them when he was their swimming coach. Assistant District Attorney Jacob Manian said he has reviewed those cases, but they are outside the statute of limitations.
"The man is clearly an evil human being who preyed on the vulnerable, if the allegations are true," said Greenfield Mayor Michael Neitzke, who said his community was shocked and outraged by the news.
Despite the severity of the allegations against Acker, he has no prior criminal record, according to Greenfield police.
But police added there had been a recent complaint about a swimming coach who had been showering with boys after practice.
Officials with the West Allis-West Milwaukee School District, which has a recreation department that offers swimming classes, had begun to investigate the complaint shortly before Acker's arrest.
Police later determined that the coach in the shower was Acker.
Acker's arrest occurred after one of the alleged sexual assault victims who is now in his 40s saw him walking into an area middle school.
That man contacted the recreation department, where Acker has worked for more than 37 years, saying he couldn't believe Acker was still working there with children.
Recreation coordinator Michele Strasser reported the allegations to police.
"Myself, our staff, our whole community - this has taken a toll," Strasser said Friday. "Kids are the most important to us, (as is) their safety."
Acker's arrest led the Wisconsin Department of Children and Families to review his time as a foster parent. He cared for two brothers who came into his home in 1999 when they were ages 9 and 11. The younger boy left Acker's home in 2002; the older one left in 2006 when he turned 18.
The two foster children were the sons of a man raised by Acker some 30 years ago, according to the man's mother, Catherine Grob.
Grob, who lives in North Carolina, said she was having problems with her son while they lived in South Milwaukee. He was getting into trouble and not coming home for days at a time, she said.
The woman said Acker was a friendly, outgoing man she came to know when he visited friends in their neighborhood.
Grob said Acker asked her if her son - whose last name is different from hers - could live with him. Grob said yes, but she checked in on her son on weekends, she said. She often stayed at Acker's home and they would all go on roller-skating outings or play board games such as Scrabble.
Acker kicked her son out of his home when her son had problems with alcohol in his 20s, according to Grob. Later, when her son had two boys of his own and couldn't care for them, Acker took them in, she said.
"He treated those boys like he was their father," Grob said. "Dan Acker was a really good guy."
Told of the accusations, Grob said she doesn't believe them.
"I hope he didn't do anything bad because I liked him a lot," she said.
Investigators found in interviewing victims this week that many men still have a concern for Acker.
"They say he was kind to them when they were younger, even though they were sexually assaulted, which is a very common phenomenon for children victimized by adults," Wentlandt said.
Parents such as Melissa Luck of West Allis said Acker was popular with the students who took his swimming lessons.
"My daughter loved him, loved him, told him she loved him all the time," Luck said of her 5-year-old daughter, Taylor, who took lessons from Acker last fall. The news of his arrest, Luck said, has been traumatic.
"Mumma, Mr. Dan broke my heart," Luck quoted her daughter as saying.
Gina Barton, John Diedrich and Ellen Gabler of the Journal Sentinel staff contributed to this report.