July 22, 2010 -- 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.
Iriana had last been seen with a man who allegedly told people he was from Honduras. He disappeared on the same day that Iriana vanished and authorities were left with few clues to his identity.
Seven years later, authorities matched DNA at the crime scene with a man who had been arrested a year earlier for forgery named Alexis Flores. Flores is now the prime suspect in Iriana DeJesus' kidnapping, rape and murder. Since authorities did not make the match until a year after his arrest, Flores was able to disappear a second time, and the alleged offender is still on the run today.
If you have any information about Flores, contact your local FBI office.
Daniel Hiers Jr. is a 37-year-old former police officer from South Carolina who was arrested for allegedly molesting an 11-year-old girl he met at a karate center. The girl reported that he had allegedly molested her repeatedly in his car and at her home, according to police reports.
Hiers was arrested for the first time for these allegations in November 2004, but did not report for a court appearance in March 2005 after posting bail. When neighbors came to look for him, they found that his wife, Ludimila, had been murdered. Hiers has not been seen since, and authorities fear he may have fled to Mexico. Investigators found his wife's car near the border in Laredo, Texas.
If you know where Hiers might be, call the U.S. Marshals at 1-800-336-0202.
Elby Hars served time for molesting his own daughter. After being released from prison, Hars allegedly enlisted his daughter as an accomplice in finding other young girls, police have charged.
After a 13-year-old girl told police in 2000 that Hars had molested her, authorities charged him with abuse. Hars disappeared, but his daughter turned herself in and is serving time in a South Carolina prison for criminal sexual conduct with a minor.
If you have information about Hars, contact your local FBI office.
John Hamilton was a trusted Little League coach and a prominent member of his community when he was arrested in Fairfax County, Va., in May 2009 after a 24-year-old man came forward saying he had been abused by Hamilton 12 years earlier.
In the course of the investigation, two other victims came forward and Hamilton was charged with sodomy, sexual battery, and taking indecent liberties with a child by a person in a supervisory relationship. The former coach did not show up for an October 2009 court date after being released on bond and he remains missing.
If you have seen Hamilton, contact Fairfax police at 1-866-411-8477.
Parents had no idea that the man they trusted with their kids had allegedly been molesting girls as young as 5 over a 20 year period, according to the U.S. Marshals Service. Authorities say Frederick McLean allegedly molested eight victims, one of whom claimed he molested her over 100 times. McLean was a devoted member of the Jehovah's Witnesses and allegedly used his position as a trusted Ministerial Servant to get close to young girls and molest them, legal documents state.
The 59-year-old auto mechanic is reported to be a loner and fled in 2004 after an 18 year old girl came forward alleging abuse. McLean had been accused of abusing girls in multiple other congregations before, but was never prosecuted by the authorities or the Jehovah's Witnesses, according to America's Most Wanted. McLean is now on the U.S. Marshals' 15 Most Wanted Fugitives list, and he was last seen near San Diego, Calif.
If you have any information about McLean call the U.S. Marshals: 1-800-336-0202.