TAMPA, Fla. -- Time is running out for perhaps hundreds of Florida convicts to ask for DNA testing that might clear them.

A two-year window opened by the state legislature for inmates to seek post-conviction DNA analysis is set to close on Tuesday. The Innocence Project, a nonprofit legal clinic researching hundreds of old cases on inmates' behalf, has little hope of completing the task by the deadline.

No other large state has a deadline this soon. Florida has the fourth-largest prison population in the country, with nearly 78,000 people behind bars.

Working since April, the Innocence Project has pored over about 400 cases and identified about 80 in which DNA testing of biological evidence might be able to clear the prisoner, said Jennifer Greenberg, one of the Florida directors. But there are about 600 more cases that still need to be examined.

Poverty and illiteracy

In most situations, Greenberg said, the inmates are poor or do not read and write well enough to pursue the matter themselves.

"There should be no statute of limitations on innocence," said Greenberg, who supports a push to extend the deadline by a year.

The Florida Bar filed an emergency request last week asking the state Supreme Court for a one-year delay, but the court has yet to act.

In Florida, DNA has cleared or freed three prisoners so far.

Generally, the convicts asking the courts for genetic analysis were imprisoned before 1996, before the use of DNA technology became common in criminal cases.

No death row inmates are on the backlog list. Unlike other prisoners, death row inmates have attorneys working on their cases from the time they are sentenced, so those who wanted testing have met the deadline.

Push for federal law

Thirty states have enacted laws addressing post-conviction DNA testing, and advocates are pushing for a federal law that sets uniform national guidelines for courts to follow when DNA testing is requested.

Florida is one of seven states with deadlines set by their legislatures for asking a court for DNA testing in old cases, said Nina Morrison, executive director of the New York-based Innocence Project.

Delaware, Michigan, New Mexico, Ohio, Oregon and Washington also have opened windows for seeking DNA testing that will close in the next year or two.

Delaware and New Mexico had one-year deadlines that expired, but in both cases the state legislatures extended them, she said. Idaho had a one-year deadline that has expired.

In Florida, staffers have worked with volunteer law students and attorneys, sifting through old cases in which biological evidence exists.

"We recognized early on that Florida was a crisis for us because of the extraordinary number of requests we received from Florida inmates," Morrison said.

The group was heartened this month when the top prosecutors in Miami-Dade, Broward and Palm Beach counties said they would continue testing DNA evidence past the Oct. 1 deadline. But there is no uniform agreement from other jurisdictions to follow suit.

Some prosecutors "are muttering that the minute Oct. 1 comes, they're going to destroy all of the tissue samples associated with these cases," said Milton Hirsch, a Miami lawyer who has helped with the project.

Willie Meggs, president of the Florida Prosecuting Attorneys Association, said the deadline was meant to clear the system of claims that are not credible. He said he expects many prosecutors will agree to reopen cases after the deadline for inmates who can show that the evidence might exonerate them.

"We're not gung-ho to change the rule, but we'll do DNA testing anywhere if it will prove their innocence," Meggs said. "There's not a state attorney that I know who's interested in an innocent person being in prison."

The trouble, Meggs said, is that DNA evidence can prove someone was not associated with a piece of evidence but does not necessarily prove the person is innocent. Sometimes other evidence is so strong that it does not matter what the DNA says.

Judges will have the final say regarding whether cases are reopened.

The Innocence Project, created by Barry C. Scheck and Peter J. Neufeld in 1992 at Yeshiva University's Cardozo Law School in New York, said post-conviction DNA testing of hair, semen, blood or other bodily fluids has exonerated 138 wrongly convicted people across the country.

In Florida, a mentally retarded man named Jerry Frank Townsend was freed in 2001 after 22 years in prison when DNA testing cleared him of rape and murder. But help came too late for Frank Lee Smith, who died of cancer in prison in 2002 -- 11 months before DNA evidence proved him innocent of a 1985 murder.

DNA testing also assisted Rudolph Holton, who walked off Florida's death row in January. The 49-year-old inmate was convicted of raping and killing a teenager in 1987 and spent 16 years awaiting execution. But DNA proved that a hair in the victim's mouth was not Holton's, as prosecutors had contended. Prosecutors concluded they did not have enough evidence to retry him.

On the Net:

The Innocence Project: http://www.innocenceproject.org

Florida Prosecuting Attorneys Association: http://www.fpaa.state.fl.us/Default.htm