LOS ANGELES -- Over two decades, the Irving-based Boy Scouts of America failed to report hundreds of alleged child molesters to police and often hid the allegations from parents and the public.A Los Angeles Times review of 1,600 confidential files dating from 1970 to 1991 has found that Scouting officials frequently urged admitted offenders to resign quietly -- and helped many cover their tracks.Volunteers and employees suspected of abuse were allowed to leave citing bogus reasons such as business demands, "chronic brain dysfunction" and duties at a Shakespeare festival.The details are in the organization's confidential "perversion files," a blacklist of alleged molesters, that the Scouts have used internally since 1919. Scouts' lawyers around the country have been fighting in court to keep the files from public view.As the Times reported in August, the blacklist often didn't work: Men expelled for alleged abuses slipped back into the program, only to be accused of molesting again. Now, a more extensive review has shown that Scouts sometimes abetted molesters by keeping allegations under wraps.In the majority of cases, the Scouts learned of alleged abuse after it had been reported to authorities. But in more than 500 instances, the Scouts learned about it from victims, parents, staff members or anonymous tips.In about 400 of those cases -- 80 percent -- there is no record of Scouting officials reporting the allegations to police. In more than 100 cases, officials actively sought to conceal the alleged abuse or allowed the suspects to hide it, the Times found.In 1982, a Michigan Boy Scout camp director who learned of allegations of repeated abuse by a staff member told police he didn't promptly report them because his bosses wanted to protect the reputation of the Scouts and the accused staff member."He stated that he had been advised by his supervisors and legal counsel that he should neutralize the situation and keep it quiet," a police report in the file says.In 1976, five Boy Scouts wrote detailed complaints accusing a Pennsylvania scoutmaster of two rapes and other sex crimes, according to his file. He abruptly resigned in writing, saying he had to travel more for work."Good luck to you in your new position," a top troop representative wrote back. He said he was accepting the resignation "with extreme regret."Scouting officials declined to be interviewed for this article. In a statement, spokesman Deron Smith said, "We have always cooperated fully with any request from law enforcement and today require our members to report even suspicion of abuse directly to their local authorities."The organization instituted that requirement in 2010. Before then, the policy was to obey state laws, which didn't always require youth groups to report abuse.In some instances, however, the Scouts may have violated those state laws. Since the early 1970s, for example, New Jersey has required anyone who suspects child abuse to report it. In several cases there, the Scouts received firsthand reports of alleged abuses, but nothing in the files indicates they informed authorities.In the 1970s and '80s, secrecy was embedded in the Scouts' policies and procedures for handling child sexual abuse.A cover sheet that accompanied many confidential files included a check box labeled "Internal (only scouts know)" as an option for how cases were resolved. A form letter sent to leaders being dismissed over abuse allegations stated: "We are making no accusations and will not release this information to anyone, so our action in no way will affect your standing in the community."That letter was included in the organization's 1972 policy on how to remove unfit leaders, which, according to an attached memo, was kept confidential "because of misunderstandings which could develop if it were widely distributed."In many cases, Scouting officials said they were keeping allegations quiet as a way of sparing young victims embarrassment.The result was that some alleged molesters went on to abuse other children, according to the Scouts' documents and court records.With 50 years in Scouting, Arthur W. Humphries appeared to be a model leader, winning two presidential citations and the Scouts' top award for distinguished service -- the Silver Beaver -- for his work with disabled boys in Chesapeake, Va.Unknown to most in town, he also was a serial child molester.A few months after Humphries' arrest in 1984, local Scouting official Jack Terwilliger told The Virginian-Pilot newspaper that no one at the local Scout council had had suspicions about Humphries.But that was not true. Records in Humphries' file show that six years earlier, Terwilliger had ordered officials to interview a Scout who gave a detailed account of Humphries' repeated acts of oral sex on him."He then told me to do the same and I did," the 12-year-old boy said in a sworn statement in 1978.Officials not only failed to report Humphries' alleged crime to police, records show -- they also gave him a strong job reference two years later, when he applied for a post at a national Scouting event."I believe the attached letters of recommendation and the newspaper write-up will give you a well rounded picture of Art," Terwilliger wrote. "If selected, I am sure that he would add much to the handicapped awareness trail at the 1981 Jamboree."Humphries continued to work with Scouts and molested at least five more boys before police, acting on a tip, stopped him in 1984. He was convicted of abusing 20 Boy Scouts, some as young as 8, and was sentenced to 151 years in prison.Humphries and Terwilliger are both deceased.The Boy Scouts' lawyers have long contended that keeping such files confidential is key to protecting the privacy of victims, of those who report sexual abuse and of anyone falsely accused. But over the years, hundreds of the files have been admitted into evidence -- usually under seal -- in lawsuits brought by alleged victims. The Times reviewed 1,600 of the nearly 1,900 files that came to light as a result of a 1992 court case.Hundreds more will soon become widely available. In June, the Oregon Supreme Court ordered the release of 1,247 of the Scouts' confidential files covering two decades beginning in 1965.The files were submitted in a 2010 lawsuit that resulted in a nearly $20 million judgment against the Scouts.