In the scrupulously clean crime lab of the Baltimore City Police, a small locked room called "the Vault" is lined with shelves stacked with giant brown bags of evidence. Paper signs are taped at the top of each column: Rapes, Homicides, Arsons, Misc.

There are more bags stored in other parts of the building, waiting to begin the long process toward finding DNA evidence that could solve a crime or free a wrongly accused person.

But with only two serologists -- one part-time -- to examine the evidence, the Vault is never empty. The lab, hobbled by a lack of resources and personnel, is struggling to keep up with the constant influx of DNA samples while trying to erase a huge backlog.

"We need more people to do the basics," says Salvatore Bianca, who does serology at the lab.

Officials got some good news this week when the Bush administration proposed to dedicate more than $1 billion over the next five years to help DNA labs catch up with a backlog of cases.

The backlog is evident in the bags of evidence stacked up at the Baltimore police lab, the first step in the long road to DNA testing. The evidence -- clothes, weapons, sometimes even fixtures like doors -- might contain bits of biological evidence that will later be transported to another stark white room, where analysts will tease out the DNA from the surrounding cell, trying to learn the genetic profile of a suspect.

Under ideal circumstances, the entire process could take as little as two or three weeks. But the city's crime lab rarely operates under ideal circumstances.

Several problems contribute to the lab's worries.

The biggest concern is a simple lack of personnel. There are eight full-time employees at the lab now, says Mark Profili, the lab's supervisor, but he could use nine more people.

The lab has only one full-time serologist and one part-time, contractual serologist. Serologists are the people who meticulously and patiently search through evidence for human traces.

"There's no typical case," Bianca says.

In his gloved hand is a silver gun. Inside the gun, Bianca had noticed a barely visible sliver of tissue.

"It could be the dead man's," he says. "We'll test this."

The gun was an unexpected addition to the workload on a recent day, a rush job that pulled Bianca away from a stretch of blood-flecked duct tape on a table behind him. Without Bianca, the tape sits, unattended.

"The state was slow to get on board with DNA (testing)," Profili says. "We just got a certified lab in here a year ago. That was on federal money."

The lab opened in 2001, after starting the certification and validation process in 1999. It has steadily logged successes since then, matching suspects and absolving innocents.

DNA analysis can be especially important in "nonsuspect" cases, where police do not have a suspect in mind. Entering a DNA profile into a national or local database might turn up a "cold hit," linking a suspect to a long-stalled case.

A cold hit from a state database turned up Roy Davis' name in the April 1998 rape and murder of Jada Lambert, 18, of Woodlawn. A grand jury indicted Davis in January.

But the technology that has led to such successes has also added to the lab's workload. Before DNA testing became a key law enforcement tool, there were fewer tests to conduct, fewer samples to collect. Now, Bianca says, the increased number of evidence tests "all adds to the time."

And the new advances reach into the past, too. Evidence from long-ago unsolved cases -- stored in case suspects ever turned up -- has now joined the backlog for testing, a sudden addition of 5,100 samples to be analyzed, Profili said. Some have been taken care of, but more than 4,000 remain, he said.

Outside grants -- like $350,000 from the Abell Foundation that was matched by the city, and $236,000 from the National Institute of Justice -- have let the lab contract out 294 nonsuspect cases over the last two years. Those cases have turned up several new leads, including an unsolved 1999 rape linked to a suspect already in custody; a 1989 rape/murder linked to Anthony Mitchell, who later pleaded guilty; and a 1997 rape linked to another already jailed suspect.

On a recent day's entries into databases, Profili said, the lab identified suspects in eight rape cases. Those cases are now being verified before charges are brought.

A new grant of about $2.5 million will allow for about 2,000 rape and 50 homicide cases to be contracted out. But Profili cautions that just overseeing that outsourcing will be a Herculean task, better suited to a task force than just to him.

"There's no way that I can oversee 2,000 (cases)," Profili says. "I will be dead and buried before that would happen."

But grants are only temporary solutions, with lab workers treading water now just to stay ahead of the influx of new evidence.

Without an expanded workforce, more equipment and more funding, the number of paper bags in the Vault will continue to grow, and the evidence there will wait still longer to be analyzed.

Leon White, one of only three full-time DNA analysts at the lab, knows the lab has been successful. But he also knows that the lab can only handle so much more work.

"There's a saturation point beyond which you can't tweak the system," he said.