AUGUSTA, Maine — Lawmakers struggling to amend Maine’s sex offender registry weighed expert testimony on Thursday aimed at determining which offenders should be included in the state’s public list and how long they should remain there.

The Legislature must act this session to fix parts of the current registration law that the state supreme court has determined violates the state’s constitution because they are applied retroactively.

But lawmakers are also looking at the law as a whole, and experts who testified before the Legislature’s Criminal Justice Committee had one simple message for its members.

“What we heard clearly today was that basing the registry on convictions alone does not work, and we should use a risk assessment model,” said Rep. Anne Haskell, D-Portland, the co-chairwoman of the panel.

In her testimony, Dr. Barbara Schwartz, director of the Department of Corrections Sex Offender Treatment program, advised lawmakers that the current system that puts a person on the sex offender registry does not reveal whether the person is a danger to society —only that they were convicted of an offense.

“A conviction is a legal thing that does not tell you what the behavior was,” she said. “I have also worked with individuals that were very, very scary. Who were very, very dangerous, and there was no mechanism for letting anybody know that I really thought this guy was a couple of days away from raping somebody.”

She said there are several tools available to measure the likelihood that someone will commit another sexual assault. She said all the available information should be used in determining who should go on a public registry — and when they might be removed from the list.

The panel discussed the use of questionnaires, polygraphs and devices to measure sexual arousal as tools that can be used to assess the likelihood of a sex offender again offending. They stressed it is important not to rely on just one testing method.

“The problem with putting everyone on there is that it is like the boy who hollered wolf,” said Dr. Susan Righthand, a clinical psychologist in private practice. “You have thousands and thousands of people, and you have no way of knowing that this is a ‘level three’ person and we should be watching out for him.”

Maine’s existing registry has two tiers, those who are on the registry for 10 years and those who are on for life. Those convicted under the 10-year requirement must verify where they live annually.

The lifetime registrants — those convicted of more serious sex crimes — must update their home and school or work addresses quarterly.

Committee members on Thursday appeared to favor a three-tier system to better assess a sex offender’s threat to the community.

Rep. Richard Sykes, R-Harrison, the sponsor of one measure to overhaul the registry, said the experts were clear that a registry should be based on risk to the community and not only on the fact they had committed a sex offense.

“Certainly the message loud and clear from this panel was that you determine risk by a variety, multiple sources of information,” he said. “Don’t make decisions based on just one risk assessment model.”

Sykes said the committee expects to act to “fix” the sex offender registry law based on the Maine Supreme Judicial Court’s ruling in the case of Eric Letalien.

The December 2009 decision upheld a ruling that Letalien, a convicted sex offender, could not be retroactively forced to become a lifetime registrant. When he was sentenced in 1996 the law permitted registrants, like Letalien, to apply for a waiver after five years.

In 1999, the Legislature changed the law to require retroactive lifetime registration. That meant that Letalien, convicted of gross sexual assault against a 13-year-old girl, had to register every 90 days for the rest of his life and could not seek a waiver.

The court’s ruling, which found the retroactive portion of the law to be unconstitutional, also stayed the effect of the decision to give the Legislature time to fix the law.