Kevin Murphy

For USA TODAY NETWORK-Wisconsin

MADISON – A Marshfield man who the government called a “serial sexual predator” was sentenced Thursday in federal court to 50 years in prison for having sex with minors and recording it.

Mark E. Bartz, 48, had sexual contact with about 15 children, many whom he babysat, during a span of three decades, according to Assistant U.S. Attorney Elizabeth Altman.

Altman wrote the court that:

Bartz set up a babysitting service in the mid-1990s to get access to six boys, ages 8 to 10 years old, repeatedly sexually abusing at least two of them during an entire school year.

As Bartz grew older, his victims grew younger, including a toddler girl and an infant boy. He photographed his victims engaging in sexually explicit conduct and posted images and videos to an internet chatroom he administered to share them and discuss child sex abuse with other pedophiles.

The chatroom also offered live sex acts between adults and children.

In one chatroom message, Bartz wrote that he engaged in a sex act with a child while the child’s parent was in the next room.

Last year, a law enforcement official saw some of the images Bartz had posted and contacted local authorities who arrested him in January.

The mother of a now three-year-old girl learned of Bartz’s abuse in a phone call from authorities while at work, Altman wrote the court. The shock and betrayal she felt caused her to quit her nursing job because she couldn’t trust to leave her children alone with anyone, “not even my husband,” said Altman while reading the mother’s statement in court.

The mother's child screams, has panic attacks and is afraid even of parades, Altman read.

“I want everyone to see how this man’s actions affected me and my family,” Altman read.

Worse than the current fear and anxiety the mother faces is knowing the pictures and videos of her daughter are posted on the internet forever, Altman said.

“They’ll know that someone can look at them every day,” Altman read.

A treasurer in a local church, Bartz acted like a “wolf in sheep’s clothing … playing off being a Christian with morals but with a black heart,” Altman read from the mother’s statement.

After writing 38 checks on a church’s bank account for his personal use, Bartz was convicted in Marathon County in 2009 for theft and placed on probation for two years, according to court documents.

Altman sought a 60-year sentence, the statutory maximum, saying it was similar to what other defendants engaging in the same conduct received and necessary to protect society’s most vulnerable individuals.

Bartz once bragged in a chatroom that he was free from being detected because his victims were too young to talk, Altman said.

Bartz’s attorney, Joseph Bugni, asked for a sentence of 22 years, after which his client would be “old and tired,” and reduced risk to re-offend.

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Bartz was born with a cleft palate, a more serious disability years ago, and endured 29 surgeries and the abuse of classmates while growing up, said Bugni.

District Judge William Conley said that challenge was balanced by having very supportive parents and was not a mitigating factor in granting Bartz any leniency.

Bartz sobbed through much of his statement saying he gave into temptation but about a year ago asked God “to stop me.”

“I’m glad he answered my prayer and there’s no more,“ he said.

Conley listed the characteristics of Bartz’s crimes of producing child pornography:

victims under 12 years of age;

abusing a toddler;

distributing explicit images on the internet;

abusing victims left in his care.

Conley said the characteristics added up to about the highest offense levels possible under federal sentencing guidelines and the highest he has seen in his several years as a judge.

Conley said he couldn’t impose a sentence that offered much chance of Bartz ever being released from prison due to the severity of his conduct.

“Virtually all of your victims were minors and all were entrusted to you by family members for you to engage in the most unimaginable conduct,” he said.