Calling him a "poster child for why sex offender registration exists," a judge Friday sentenced a Mills man to 18 to 20 years in prison for molesting a boy.

Melvin Gregg was already a convicted sex offender in Iowa before he pleaded no contest earlier this year in Natrona County to charges he sexually abused an elementary school-aged boy last fall, prosecutors say.

Judge Scott Skavdahl said he could not accept that Gregg was now "begging for treatment" when nothing prevented him from getting treatment before his latest crime.

"You had the opportunity and now I have three victims," Skavdahl said, referring to the boy in Mills and victims in Iowa.

Skavdahl sentenced Gregg to the maximum time allowed under Wyoming law.

Mills police arrested Gregg in November after the boy came forward and told a relative about the abuse, court records show. Gregg initially denied any wrongdoing to a Mills investigator. However, after being told the boy would have to testify in court, Gregg admitted to the abuse.

In court Friday, he apologized to his victims.

"For the life of me, I wish I knew what was wrong with me," he said, adding that he hoped to get some counseling.

Assistant Natrona County District Attorney Michael Schafer called the abuse "totally inappropriate and despicable acts" that mirrored what Gregg had done in Iowa several years before.

"I don't think the defendant understands the extend of the harm he has done," Schafer said.

Gregg's attorney, public defender Kimberly Corey, said her client was heartbroken over what happened and was also a victim of abuse. She asked for a prison sentence of five to 15 years.

"He is just begging for treatment," she said.

Reach crime reporter Joshua Wolfson at (307) 266-0582 or at josh.wolfson@trib.com.