ANNAPOLIS - A bill pushed by Gov. Martin O'Malley to require DNA collection from people arrested for certain violent crimes in Maryland is expected to advance to a final vote no later than Saturday thanks to amendments alleviating civil liberties concerns from the Legislative Black Caucus and others.

But the legislation is now facing some opposition from early supporters who feel the amendments adopted by the House Friday are contrary to the bill's intent because they allow for testing current prisoners and expunging some samples.

Originally, the bill would have allowed officers to collect DNA from individuals at the time of arrest, and have that information added to state and federal databases.

But the black caucus, the American Civil Liberties Union and the National Association for the Advancement of Colored People opposed the proposal because they said it conflicted with the presumption of innocence spelled out in the U.S. Constitution.

The groups also said racial minorities are arrested in connection with violent crimes three times more often than are whites and that would add up to a heavier representation of those groups in the state's DNA database.

The amendments do a good job of addressing the caucus' concerns and those of the civil rights community, said Delegate Herman Taylor, D-Montgomery, at a committee hearing Thursday.

The changes to the bill allow DNA to be taken only when a person is charged with a crime. The samples can be entered into the central DNA database only if the person is indicted.

Other amendments require that sample analysis be done in a timely fashion and provide for the automatic expungement of samples if an individual is found not guilty.

The governor's office worked with both the committee and caucus on their amendments to address their concerns, said Christine Hansen, a spokeswoman for O'Malley.

Despite the attempts at compromise, the ACLU continues to object to the bill.

"The amendments do not address the fundamental Fourth Amendment violation that occurs when you take DNA from someone who hasn't been convicted for a crime and when that DNA is unrelated to the crime for which they're arrested," said Cindy Boersma, legislative director for the ACLU of Maryland.

Some delegates said the new compromises go too far. For example, one change would allow prisoners to request DNA tests in order to prove their innocence.

"This was bad practice in that it made a drastic expansion of the scale of the legislation," said Delegate Christopher Shank, R-Washington, a co-sponsor of the original bill who voted against the addition of the amendment allowing for DNA analysis for individuals already in prison.

The bill was meant only to address the addition of samples to the system, he said, and although he is not opposed to the idea there should have been hearings on the issue.

"This is not the way we pass a substantial piece of legislation," Shank said.

Other objectors included delegates Doyle Niemann, D-Prince George's, and Anthony O'Donnell, R-Calvert, who said the amendments would increase the backlog of DNA evidence to be tested.

O'Donnell was also a co-sponsor of the original bill but said during Friday's debate that the amendments may have changed his mind.

Another co-sponsor, Delegate Richard Impallaria, R-Baltimore, also questioned the expungement of samples when evidence like fingerprints are never removed from police records.

DNA is a much more reliable system of identification than fingerprints are and genetic information should be kept on record the same way, Impallaria said. Proponents of collecting DNA argue that a database could be used to solve crimes as well as exonerate the innocent.

The governor has been concentrating on public safety in his efforts to regain support. He could benefit politically if legislators pass the bill, which some have called unusually conservative compared to other legislation he has introduced.

O'Malley has been losing support among Maryland voters since the tax hikes of the November special legislative session when lawmakers met to work on closing a $1.7 billion gap in the state's budget.

The black caucus comprises about a quarter of the state's lawmakers and represents support O'Malley cannot afford to lose.

Beyond the State House, polls by Gonzales Research & Marketing Strategies over the course of O'Malley's tenure show that his strongest support has come consistently from African-American voters - an important constituency for the governor and one that could be alienated by lingering concerns over the bill.