A man known by law enforcers as "Diaper Boy" is under investigation once again after reports he pulled down his pants in front of young children, according to investigators, and exposed a baby's diaper that he wears as an undergarment.

Investigators say the man's actions raise big red flags for them. But they aren't sure what to do in this case, because two previous incidents in 2007 and 2008 that were very similar were both thrown out of court.

The man, 31, is being investigated by the Salt Lake County Sheriff's Office in an incident earlier this week in Holladay.

The man approached a 4-year-old boy and his two young friends riding bicycles in the boy's driveway, said sheriff's Lt. Don Hutson. The registered sex offender offered to show the boys his diaper and proceeded to pull down his pants and do just that, he said.

The case will be reviewed by the Salt Lake County District Attorney's Office for potential charges. But unless those charges are filed, the sheriff's office is reluctant to arrest him.

Last August, the man was charged in 3rd District Court with lewdness involving a child. The 5-foot-3, 100-pound man allegedly made his diaper very visible to young children at the East Millcreek Recreation Center, 2230 E. Evergreen Ave. (3435 South) while he got a drink of water.

That came on the heels of another similar incident in October 2007 which led to charges in Justice Court in Holladay. In that case, the man was sentenced to the maximum 180 days in jail.

He was convicted in 2000 of lewdness involving a child, forcing him to become a registered sex offender in Utah. But the 2008 charge of lewdness involving a child was dismissed after a judge ruled that showing a diaper to children was not on the same level of distress as was a person exposing genitalia to children or performing a sex act in front of them.

After the case in state court was tossed, the judge in the justice court case followed suit.

But the sheriff's office said the man's continued behavior should be a concern for everyone.

"Any parent would be concerned if an adult male is pulling his pants down in front of children," he said.

Prosecutor Alicia Cook said despite the recent setbacks, her office would continue reviewing all cases involving him that are put before them.

"The most concerning thing is he's approaching children in public places," she said. "He's approaching kids under circumstances that are very concerning."

Cook said her office would look through the facts of each case and see if they constitute lewdness charges as defined by the law.

E-mail: preavy@desnews.com