OLYMPIA — DNA evidence can be the turning point for a post-conviction appeal, but whether or not it still exists years later is often no guarantee.

A bill that has passed the House and is awaiting action in the Senate would require DNA collected in any felony case charged as a violent or sex offense to be preserved through the length of the offender’s sentence, including post-prison community custody. In cold cases, where no one has been charged or convicted, the DNA would have to be maintained throughout the statute of limitations for the crime.

Under current law, there is no requirement to preserve DNA evidence after a conviction, though defense attorneys can seek a court order to do so.

“People find it astonishing that this evidence can just be thrown away,” said Lara Zarowsky, policy director for the Innocence Project Northwest at the University of Washington’s Law School.

Rep. Tina Orwall, the sponsor of House Bill 1069, said she was indeed surprised to learn there weren’t standard protocols across the state. Orwall, a Democrat from Des Moines, had previously sought an 18-month moratorium on the destruction of DNA evidence in some criminal cases. The measure she introduced last year would have also created a work group to recommend permanent, statewide standards for preserving DNA material. It was later amended to remove the moratorium but still never came up for a vote in the House. Orwall said that she and other lawmakers and others met four times for work groups on the issue between June and January to discuss this year’s approach.

“At the end of the day, we do want justice,” she said. “We don’t want innocent people in prison and we don’t want violent offenders on the street.”

Zarowsky said most states have varying laws on how long to preserve biological evidence and that Washington is one of several that don’t automatically preserve DNA for serious felonies. In Washington, once convicted, defendants must file motions to have evidence preserved for use during possible appeals.

Because preservation rules may differ from jurisdiction to jurisdiction, or even agency to agency, Zarowsky said there is no guarantee that DNA evidence will be available for testing if cases are appealed. She said that her group reviewed about 70 potential DNA cases between 2011 and 2013 and found that in 25, including murder and rape prosecutions, biological evidence was destroyed in eight cases and lost in one.

“This is one of those areas where it’s clear that we need state guidance on what the baseline should be,” she said.

Orwall’s measure passed the House on a bipartisan 77-20 vote last month, and has been referred to the Senate Law &Justice Committee, where it will have a public hearing on Thursday.

Mitch Barker, executive director for the Washington Association of Sheriffs and Police Chiefs, said that the bill is still a work in progress and that his organization has been talking with Orwall and others on some of the language concerning statute of limitations for cold cases.

Barker noted that for some crimes, like murder, there is no statute of limitations, and he said that the law enforcement community wants to make sure “we’re not holding stuff forever.”

Zarowsky said that new language being considered as the bill moves through the Senate would address that, putting the timeframe for holding the DNA at 99 years or the statute of limitations, whichever is shorter.