The number of convicted sex offenders living in Keansburg has dropped from around 40 to 20-something because of a local rule that imposes restrictions on where those offenders can live, authorities said.

Some sex offenders moved to other towns in Monmouth County, some moved to other New Jersey counties and a few moved out of state, according to police.

A few more offenders have recently been given summonses, letting them know they also must move because they are in violation of Keansburg's residency restrictions, authorities said.

Keansburg is one of at least 45 communities in Monmouth and Ocean counties that enacted ordinances since 2005 limiting where convicted sex offenders could live. In more than a dozen municipalities, including Keansburg and Hazlet, the residency restrictions do not apply to convicted sex offenders who owned their own homes when the rules were enacted.

While there has been litigation over local ordinances in other New Jersey counties, John Bennett, the borough attorney, said Keansburg is not currently involved in any litigation and its ordinance remains in effect.

After Keansburg's governing body passed its initial ordinance in 2005, police told convicted offenders about the new rules.

Those with leases were told they would be allowed to remain until the leases expired. Those without leases were given grace periods to find other housing.

Some relocated right away.

The ones who moved, left town because the ordinance covers such a large swath of the borough, Sgt. Kevin White said.

Those who remained were given summonses.

Then a lawsuit was filed against the borough on behalf of a tier-one offender, and all of the initial summonses were put on hold, White said. A tier-one offender is one deemed to be at a low risk of offending again.

Last year, the borough council amended the ordinance, so it only applied to tier-two and tier-three offenders — those at a moderate and high risk of offending again.

That's when the tier-two and tier-three offenders, who were living in restricted zones in the borough, relocated to other communities, other counties and other states, White said.

The summonses initially issued to tier-one offenders were dismissed and they were allowed to remain in their homes.

White said when the ordinance was passed there were around 40 offenders living in Keansburg, but after the new rules were put into effect, the number probably dropped below 30. Now, that number is in the 20s, he said.

"It fluctuates," White said. "We get people who come into town, and others who move out for other various reasons."

Meanwhile, in nearby Hazlet where two offenders, who were not homeowners, lived in restricted zones, that municipality's rules have not been an issue.

Both offenders moved, unrelated to the passage of the ordinance, and sex offenders who came to the community after the rules were enacted have not moved into the restricted zones, police said.