Ray Ojeda stalked girls. 

In 1997, he followed a 15-year-old home from school. He grabbed her, held her at gunpoint and sexually assaulted her -- then shot her in the head and threw her in Colorado's Platte River, according to court records.  

She survived. Despite her injuries, she walked a half-mile -- 1,000 steps -- to a highway, and flagged down a car for help. 

Nearly two decades after she was left for dead, justice was at last delivered when officials were able to check the DNA from a previously untested rape kit against a federal database. Ojeda was sentenced Monday to 144 years in prison. 

This case is the exception.

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An untold number of rape cases -- by some estimates, in the hundreds of thousands -- remain unsolved because the rape kits used to collect critical evidence sit untested and gathering dust in police departments across America, despite $1 billion in taxpayer money approved to clear the massive backlog.

Critics blame the Justice Department, claiming it simply is not sending the money where it needs to go.

"It's a tragedy that evidence from perhaps hundreds of thousands of unsolved rape cases has never been tested for DNA," Scott Berkowitz, president and founder of the Rape, Abuse & Incest National Network, told FoxNews.com.

A comprehensive investigation by USA Today and its media partners uncovered at least 70,000 neglected kits in more than 1,000 police agencies. A state-by-state review suggests those numbers are on the conservative side, with 34 states reportedly admitting they have no idea of the number of untested kits.

Federal officials pushed back against USA Today's report, saying it "greatly mischaracterizes what has been, and continues to be achieved by the Department of Justice to address un-submitted sexual assault kits."

Rape kits contain forensic DNA evidence collected from victims during an often invasive process that can take up to six hours to complete. Testing DNA evidence in a timely manner helps identify suspects, leads to more prosecutions and in some cases exonerates those wrongly accused.  

But none of that can take place if the kits aren't tested -- the $1,000 price tag for each test, though, can stress the budget of a local police department.

Sen. John Cornyn, R-Texas, recently sent Attorney General Loretta Lynch a letter demanding the Department of Justice address the issue. "Victims of sexual assault should not have to wait unnecessarily for justice," he wrote in the June 29 letter.  

Cornyn and Sen. Michael Bennet, D-Colo., were behind landmark federal legislation that led to the passage of the Sexual Assault Forensic Evidence Reporting (SAFER) Act. Signed on March 7, 2013, SAFER requires at least 75 percent of the $1 billion appropriated in the law to be directed toward reducing the massive rape-kit backlog, and increasing the capacity of labs processing sexual assault kits through 2018.

The problem, victims' advocates and lawmakers argue, is that the DOJ is spending the money on other programs.

"Congress has provided the funds to fix this problem, but over the past 10 years a large part of that money has been used for other criminal justice or administrative purposes," Berkowitz said. He said the law passed by Congress set "very specific spending guidelines to ensure that the vast majority of the money goes to casework," adding: "We'd like to see the Justice Department follow that formula and solve this problem once and for all."

But an official with the DOJ's National Institute of Justice told The Washington Examiner the department "has not received appropriations specifically to implement" the DNA backlog grant program.

Instead of waiting for the Justice Department, some states have taken matters into their own hands.

Colorado, for instance, passed a law in 2013 requiring law enforcement agencies to analyze within one year all of their 3,542 untested rape kits -- a deadline that was met, Colorado Bureau of Investigation spokeswoman Susan Medina told FoxNews.com.

"It was a way for us to really collaborate with our law enforcement partners," Medina said.

While larger metropolitan cities are starting to step up and cut down their backlogs, stark inconsistencies still exist in how rural communities handle rape kits. 

Decisions on which kits are tested -- and when and how -- are often left to the discretion of police departments, leaving justice at the discretion of dollars and local policy.