Undercover police officers spent Wednesday at Wilderness Park.

What they found may seem a surprise: They arrested 10 men on suspicion of public indecency or sexual assault during the daylong detail in southwest Lincoln.

The men ranged in age from 39 to 73. Seven were Lincoln residents; the others were from Omaha, Seward and Kearney, Police Chief Tom Casady said.

“In these 10 cases, basically, undercover police officers in the park were approached by men who either groped the officer or exposed their genitals or both,” he said.

In two cases, he said, men were masturbating in a place where they could be seen.

It’s no secret to police that people go to certain Lincoln parks looking for anonymous sexual encounters, Casady said.

“Wilderness Park is not the only place in Lincoln that’s had this kind of a problem from time to time,” he said. “We try to do a little bit of enforcement on occasion to keep this from becoming a problem.”

It started happening at Wilderness Park in the late 1980s, and before that at Van Dorn Park and the Interstate 80 rest stop, Casady said. Cities across the country deal with the same problem.

In Lincoln, it’s illegal to have sex in a public park, he said. Even if both participants are willing, it’s still indecent exposure.

And Casady said it’s not a victimless crime.

“What I get concerned about is that people do, from time to time, stumble across these things going on inadvertently. … They’re there to ride their horse or go for their run or ride their bike or just use the restroom, and they get confronted by this kind of a situation.”

That happened to him once, years ago, with his son, he said.

Police also have received complaints — including one during Wednesday’s detail — regarding nearby Standing Bear Park, Casady said. The caller said he was on his lunch break when a stranger took his pants down in front of him.

Officer Katherine Finnell said there’s been a lot of activity lately, and isolated parks on the outskirts of the city tend to be targeted.

In the detail Wednesday, she said, undercover officers saw one man ride his bike up to a car and, after a short conversation, pull his pants down and begin masturbating. Other men, she said, approached male undercover officers walking in the park and groped them.

Ultimately, six men were arrested on suspicion of third-degree sexual assault and four on suspicion of public indecency, roughly between 8 a.m. and 4 p.m. Wednesday.

Third-degree sexual assault is a misdemeanor punishable by up to one year’s imprisonment. Public indecency is punishable by up to six months in jail.

Reach Lori Pilger at 473-7237 or lpilger@journalstar.com.