American Indian tribes have two years to start tracking sex offenders themselves or take part in their state's registration system after an attempt to delay a requirement of the Adam Walsh Act failed.

Congress passed the act one year ago to protect children from predators by setting up a national Internet database designed to let law enforcement and communities know where convicted sex offenders live and work.

There are an estimated 500,000 sex offenders in the United States and as many as 100,000 are not registered.

Indian tribes had until Friday to tell the Department of Justice if they plan to establish their own tracking system or allow states to do it. Tribes that didn't indicate their plans will default to state jurisdiction.

An effort in Congress to delay that notification date by one year -- to give tribes more time to decide -- failed, so tribes now have until July 27, 2009, to have their own system in place or an agreement with states.

Eric Antoine, in-house attorney for the Rosebud Sioux Tribe, said the tribal council felt it wasn't consulted before the law passed and voted to handle its own sex offender registry.

"It's a question of tribal sovereignty for the tribal council," he said.

The tribe hopes that some federal funding will be available to help cover the cost, Antoine said.

Kim Lowry, acting director of the Office of Communications in the Office of Justice Programs in Washington, said the Department of Justice has communicated through e-mails, meetings and mailings to more than 560 tribes.

Though tribes had until Friday to indicate their intentions, those that indicated they want to comply with the law's requirements on their own can still let the state handle it if they choose, she said. The tribes are not handing over sovereignty, Lowry said.

"They (tribes) want to do this to protect everybody. It's just figuring out how it's going to be done," Lowry said.

Virginia Davis, associate counsel for the National Congress of American Indians, agreed that most tribes will likely let the states handle the sex offender registry.

She said her organization sought the year delay so there was more cooperation going into the project.

"For this to work in Indian country, the states and the tribes are going to have to work together," Davis said.

The tribes do want to prevent sex offenders from seeking refuge on reservations, she said.

"The tribal leaders feel really strongly about this issue and are concerned about keeping their communities safe. We have high rates of sexual assault in Indian country and this is an issue we care about," Davis said.

Marty Jackley, U.S. attorney in South Dakota, said all nine tribes in South Dakota indicated they'll form their own sex offender registry but might still let the state handle it.