Back in 1999, John Sawn's sexual attack on a woman in New York earned him eight years in prison.

But the crime that may bring him a longer sentence was his move to Virginia.

Sawn is facing a possible 10 years in the penitentiary for failing to update his address on state sex offender registries. He's among the first suspects charged in a new effort by the U.S. Marshals Service in Roanoke, which began targeting sex offenders after Congress passed the Adam Walsh Act last year.

The arguments in Sawn's case, which is scheduled to be heard Tuesday in Lynchburg, echo those being heard around the country as federal courts sort out the newest regulations for sex offenders.

For investigators and prosecutors, it's a matter of "getting these dangerous predators off our streets and away from our children," William Fallon, chief deputy U.S. marshal for the Western District of Virginia, wrote in an e-mail.

For critics, the new, tougher requirements aren't being implemented fairly -- "holding people criminally liable for things that weren't a crime a year ago," said Sara Noonan, a researcher with the federal Office of Defender Services.

For Sawn, a stoop-shouldered man with heavily tattooed arms and close-cropped brown hair, mustache and goatee, his legal troubles stem from a fishing expedition -- literally -- gone very wrong.

Keeping track

One of the goals of the Adam Walsh Act was to unify the different state sex offender registries like the one the Virginia State Police maintains online. The legislation mandates that states have until July 27, 2009, to implement a series of measures, including sorting sex crimes into three tiers, with the most serious offenders required to update their registry information every three months for the rest of their lives.

The law changed the federal penalty for moving to a new state and failing to register from a misdemeanor charge punishable by up to a year in prison to a felony carrying a possible 10-year sentence and a fine of up to $250,000.

There is no way to know how many sex offenders have failed to keep their registration information current. National estimates range upward to about 100,000, U.S. Marshal Wayne Pike said.

Since last fall, marshals based in Roanoke have worked with a variety of other agencies, including Virginia State Police and local police, to track down cases such as Sawn's. So far, 28 people have been charged with a variety of state and federal crimes.

Seven of these people, including Sawn, were charged under the Adam Walsh Act with being sex offenders who crossed state lines and failed to register. One of the seven, Richard Dean Hinen, a Kingsport, Tenn., man who didn't register when he moved from Virginia, was convicted in May in one of the first Adam Walsh Act jury trials in the nation.

Two others of the seven have pleaded guilty, and charges were dismissed against two. None of those convicted has been sentenced yet.

Deputy Marshal Greg Burnett, who is leading the effort, said the new emphasis on tracking sex offenders is off to a good start. But it likely will become a higher-profile program in the future, he said. Marshals offices are creating new senior investigator positions to focus on sex offenders. Burnett said he'll apply if such a position is approved in Roanoke.

"It's the whole game now," he said. "We can grab fugitives all day long ... but you're the case officer now."

Gone fishing

The case against Sawn resulted from the interagency cooperation that Pike, Fallon and Burnett say has been the key to new efforts against sex offenders.

Stakeouts and chases are part of the picture, but much of the effort has been more routine -- building communication links, setting up new procedures to run checks on people brought into custody to see if they're supposed to be registered as sex offenders.

In January, federal investigators say, Sawn left New York and moved to Lynchburg. New York police, who were alerted when he didn't make his scheduled update to his sex offender registration, tracked him to an apartment, but he had already moved on. He had not contacted Virginia authorities to register as a sex offender.

Sawn's capture came after a Virginia game warden found him fishing on private property, according to court filings. Sawn was searched, and a bag of marijuana was found. He gave a false name and fled.

But just over a week later, on April 7, four game wardens tracked him down at the Timberlake Motel in Campbell County. Court filings say Sawn told the wardens he had run because he was wanted in New York for failing to update his registry information.

In May, he was convicted in Bedford County of possessing marijuana, falsely identifying himself and obstructing justice. His registration issues were left to federal authorities.

Critics of the Adam Walsh Act say it should be up to states to prosecute sex offenders who don't meet registration requirements.

Like others around the country, Sawn's case falls into an apparent gray area in the act, which is its requirements for offenders who, like Sawn, committed a sex offense before the act was approved.

Larry Shelton, the federal public defender who is representing Sawn, argued in a motion to dismiss the case that the Adam Walsh Act didn't apply to Sawn at the January date when he is accused of moving and not registering. Shelton's argument is that the act assigns the U.S. attorney general to issue regulations about how the Walsh Act would be applied to this group of offenders, and the attorney general did not do this until the end of February.

Assistant U.S. Attorney Craig Jacobsen has a different interpretation of the attorney general's role, saying in his response to Shelton's filing that the act gave a much narrower direction to create procedures only for offenders whose crimes had not previously required them to register.

In June, a federal judge in West Virginia was convinced by an argument like Shelton's and dismissed an Adam Walsh Act case.

But last month, Judge Norman Moon rejected a similar argument in the case of another man charged under the Adam Walsh Act. He was following the lead of the senior federal judge for the Western District of Virginia, who was not convinced when the argument was made in Hinen's case.

All three judges are part of the federal 4th Circuit, and the appellate court may eventually resolve the discrepancy.

Similar inconsistencies are cropping up across the country, Noonan said, although none has yet reached the federal appellate courts, much less the U.S. Supreme Court. Other issues that defense attorneys have tried to raise with the Adam Walsh Act include whether the federal government properly has jurisdiction over sex offender registry issues, or whether the act unconstitutionally adds retroactive criminal penalties.

Sawn's jury trial has already been removed from the docket. Tuesday's court date, originally a session for the judge to hear arguments about whether to dismiss the case, now has a schedule note that a conditional guilty plea may follow.