After days of being chained up, sexually abused and raped, 16-year-old Andrea Hood escaped her two attackers and ran to the police in Hillsboro, Ore.
Authorities conducted an investigation and searched the house where Hood was held captive and identified Paul Erven Jackson and his half-brother, Vance Roberts, as Andrea's alleged attackers. Police also claim they found evidence that a previous sexual assault of a similar nature had occurred in the house.
That was 1990 and the men fled before trial, not to be heard from until 2006 when Roberts turned himself in to Hillsboro police. He is currently serving a 108 year prison sentence for kidnapping, rape, and other charges.
But Jackson remains at large.
Jackson is just one of an uncounted number of alleged sex offenders who have jumped bail or otherwise escaped authorities since allegedly committing a crime.
David Harlow is the chief of the Sex Offender Investigations Branch at the U.S. Marshals Service, which tracks down fugitives like Jackson as well as convicted sex offenders who have failed to register. He estimated that there are 750,000 convicted sex offenders who should be registered, and up to 125,000 who have failed to register.
How many alleged sex offenders are running from the law prior to a conviction is more difficult to determine, he said, but they have tracked down roughly 20,000 fugitive sex offenders in the last year.
Harlow said sex offenders can be difficult to track down and often appear harmless. "They're very good at hiding in plain sight until someone trusts them with their children and then they victimize someone," Harlow told ABCNews.com.
ABCNews.com compiled a list of some of the most wanted alleged sexual predator fugitives, using information from the Marshals Service, the FBI and America's Most Wanted, an organization that helps track down criminals and missing children through a weekly television show of the same name.
Harlow said tips from the public often lead to the arrests of these criminals. "When a child is a victim, people are usually very helpful," Harlow said. "We get a lot of information from the public, which is great, and that is exactly what we need to do."
If you have information about Jackson, call the Hillsboro police at 503-615-6751. You should alert authorities if you have information about any of these other suspects:
A former gymnastics teacher named James Bell fled Rhode Island in 2004 after he was arraigned on seven counts of second degree child molestation. The 56-year-old allegedly molested three girls, ages 9 to 13, while working as a gymnastics coach at a YMCA in Middletown, R.I.
Bell was arrested in Allyn, Wash., and brought back to Rhode Island in 2003 for court proceedings. After being released on bail, Bell failed to appear in court for a pretrial conference in July 2004, according to the FBI. The United States District Court of Rhode Island issued a federal arrest warrant for Bell in January 2006, and authorities continue to search for him.
If you have any information about Bell's whereabouts, contact your local FBI office.