DALLAS (CBSDFW.COM) - She was only six years old and looking forward to a sleepover with her young cousin.

It was 1993 in Dallas. It was going to be fun.

Maybe someone would take them to McDonald's where they could get a Happy Meal. The toy treat that year included those cool mini Barbie dolls. What a great collection: "My First Ballerina," "Hollywood Hair," "Secret Hearts."

Instead, hearts would be broken. The cousins stayed home. A man was there. Night turned to nightmare.

"I just remember him lying in the bed. I knew it wasn't right. I was scared," she told CBS 11's Ginger Allen.

He has never been punished for what she says he did that day, 17 years ago. In fact, from all accounts, it wasn't until last Saturday – Feb. 12, 2011 – that investigators tried to arrest him for allegedly sexually assaulting her.

Federal immigration agents and investigators with the Dallas County District Attorney's Office did not find him at an East Dallas apartment, where he reportedly had been staying, but he had been seen in the area a week or two earlier.

Though no arrest was made, the lead was encouraging, especially on a day when the agents and DA investigators worked hard to find more than 40 other men, each suspected of child abuse in Dallas County … and each able to escape justice for years because of a questionable law enforcement practice uncovered by CBS 11 News.

"It is horrible," Dallas County District Attorney Craig Watkins said, referring to his discovery of a backlog of thousands of criminal investigations – 720 of them child abuse cases, many alleging sexual assaults – that were filed away, collecting dust, in a packed storeroom.

Watkins, who made the discovery after he took office in 2007, said those cases went unsolved, with little or no effort to make an arrest, in part because of a decades-long agreement that allowed police to work a case and seek an indictment without having a suspect in custody.

Once indictments were returned in investigations, he said, the efforts to find and capture suspects were often turned over to an understaffed sheriff's warrants division, which was unable to devote the time or resources needed to track them down, even in the most heinous of crimes – attacking children.

In response to an interview request with CBS 11 News, Kimberlee Leach, spokeswoman for the Dallas County Sheriff's Department, stressed the large workload, saying in a statement that the department "has more than 200,000 warrants to serve at any given time." Leach added, however, "Warrants for violent sex crimes are given high priority, and every effort is made to locate the offenders."

That does little to soothe the feelings of the victim who agreed to share with CBS 11 the terror of her attack, and the years of torment, knowing he was still free.

"You would think a child being touched by a grown man; they would have done more to put him away," she said. She is upset, she said, that her case did little more than collect dust in a storeroom.

"I was put on the shelf, you know. I was only six."

Watkins said he reversed the old case-filing policy, which was practiced by previous district attorneys Bill Hill, John Vance and Henry Wade, and now requires that all police agencies in the county make an arrest, or at least work hard to make an arrest, before they bring a case to the DA's office for an indictment. Vance and Wade have since died, and Hill declined repeated requests for an interview with CBS 11.

Toby Shook, who was Hill's felony trial chief and who is now in private practice, said neither his former boss nor the old policy should be blamed for arrests not being made in serious criminal investigations.

"If you're going to blame anyone, you're going to have to blame law enforcement," Shook said, adding: "It's their job to apprehend criminals. We can't send our lawyers out to find them."

However, Deputy Chief Craig Miller, who is head of the Crimes Against Persons Division of the Dallas Police Department, said it is nothing more than sad "reality" that some criminals get away with the crimes they commit, even the ones involving small children.

Asked to compare the old policy in place before Watkins took office, and the one he implemented once he became DA, Miller said, "Either way, it doesn't impact the Dallas Police Department on the way we do things."

"We make every attempt we can to find bad guys," the deputy chief said, noting that the DPD makes between 60,000 and 70,000 arrests each year.

The victim who talked with CBS 11 said she is glad that, finally, police are looking for the guy who she says molested her.

"Now I feel like I matter," she said. "Hopefully, when they go out to catch him, they will get him … he needs to be behind bars."