TULSA, Okla. (AP) - A newspaper analysis of state Department of Corrections data indicates that registered sex offenders who once lived in Tulsa are moving to rural counties.

Others appear to be moving underground, the analysis by the Tulsa World showed.

In recent years, the state has imposed tough residency restrictions on sex offenders, prohibiting them from residing within 2,000 feet of schools, parks or day care centers. Since 2005, just before those laws took effect, the number of registered sex offenders in Tulsa has dropped from almost 600 to about 350.

Meanwhile, of the 443 sex offenders registered in Rogers, Creek, Wagoner and Osage counties - all of which border metropolitan Tulsa County - 60 of them lived in Tulsa County in 2005, the DOC data indicates.

"What we're finding is people are moving out of the cities because they are having a hard time finding a place to live under the statutes," Osage County Sheriff Ty Koch said.

In Osage County, the number of registered sex offenders has risen from 40 in 2005 to 116. Jeanie Brown, a warrants specialist for the Osage County Sheriff's Department, said the rural nature of the county, along with its proximity to Tulsa, is the reason for the increase.

Koch said the increase is making it tougher for his staff to track registered sex offenders, especially those who give invalid addresses. He said someone from his office visits the homes of sex offenders at least once a year to make sure they have provided a correct address.

One registered sex offender, who spoke to the World on the condition of anonymity, said he moved from an apartment in Tulsa to a relative's house in Osage County. The nearest school is 3_ miles away and he commutes almost 40 miles to work in Tulsa.

"I like looking out in the morning and seeing all the deer," he said.

The man said that fewer sex offenders will register if authorities make the restrictions even tighter, and "it's better to know where people's at than not."

Tulsa County has seen a drop in registered sex offenders from 800 to 491 since 2005, which Tulsa Police Sgt. John Adams attributed to tougher residency restrictions that has made about 85 percent of the city off-limits to sex offenders.

But he also said that his unit has seen a large increase in residency violations, an indication that some sex offenders are living in Tulsa illegally.

The DOC data also showed that of the almost 900 sex offenders whose whereabouts are unknown, 157 committed their sex crime in Tulsa County and 144 did so in Oklahoma County.