Jeffrey Epstein, the New York financier, managed to evade federal prosecution a decade ago in a Florida sex case involving dozens of teenage girls, in part by agreeing to register as a sex offender.

But for a man with many residences, and many high-powered lawyers, registering as a sex offender was not the blanket penalty it might seem.

He did register in Florida, where he pleaded guilty to two state felony charges. But in New York, where he owns one of Manhattan’s most expensive mansions, he managed to avoid check-ins with authorities by changing his official residence to the Virgin Islands.

And in New Mexico, where he owned a palatial residence south of Santa Fe, he was able to avoid inclusion in the state’s registry entirely.

That state’s relatively cursory investigation took into account only a police report which indicated, authorities said, that the underage victim in the case to which Epstein pleaded guilty in 2010 was 17 — the age of consent in New Mexico — though the girl whose report launched the investigation against him was just 14.

Jeffrey Epstein: Controversies surrounding paedophile billionaire Show all 9 1 /9 Jeffrey Epstein: Controversies surrounding paedophile billionaire Jeffrey Epstein: Controversies surrounding paedophile billionaire Jeffrey Epstein in court Billionaire financier Jeffrey Epstein attends court as he pleads guilty to solicitation and procuring a person under the age of 18 for prostitution, 2008 Zuma/Rex Jeffrey Epstein: Controversies surrounding paedophile billionaire Jeffrey Epstein in court Billionaire financier Jeffrey Epstein pleaded guilty in 2008 to felony solicitation and procuring a person under the age of 18 for prostitution. He was sentenced to 18 months in jail. Epstein, allegedly paid several girls under the age of 18 in return for naked massages at his Palm Beach, Florida estate Zuma/Rex Jeffrey Epstein: Controversies surrounding paedophile billionaire Jeffrey Epstein's car Jeffrey Epstein is whisked away from the Palm Beach County jail in a black car shortly after 6am on 22 July 2009. Epstein left the jail through the sally port, where prisoners are brought in, rather than through the main doors where prisoners are routinely released Zuma/Rex Jeffrey Epstein: Controversies surrounding paedophile billionaire Jeffrey Epstein's mugshot Billionaire Jeffrey Epstein's mugshot, taken after he was indicted for soliciting a prostitute on 26 July 2006. Beginning in mid-March 2005, Epstein became the target of a sexual battery probe conducted by the Palm Beach Police Department, according to the affidavit, which alleges that Epstein paid a series of underage girls to engage in sexual activity with him. In a 2002 New York magazine profile of Epstein, Donald Trump called the moneyman a 'terrific guy' who 'likes beautiful women as much as I do, and many of them are on the younger side.' Epstein, who reportedly runs a multibillion-dollar investment fund, travels in his own Boeing 727 (upon which he has transported Bill Clinton to Africa) and owns a 45,000-square-foot mansion on Manhattan's Upper East Side Palm Beach County Sheriff's Department Jeffrey Epstein: Controversies surrounding paedophile billionaire Jack Goldberger, Jeffrey Epstein's attorney Jeffrey Epstein's attorney, Jack Goldberger, talks with reporters gathered outside the Palm Beach County jail on 22 July 2009 after Epstein was whisked away from the jail in a black car Zuma/Rex Jeffrey Epstein: Controversies surrounding paedophile billionaire Jeffrey Epstein Florida Police department sexual offenders database picture of Jeffrey Epstein taken in 2013 Jeffrey Epstein: Controversies surrounding paedophile billionaire Jeffrey Epstein's mansion His Palm Beach mansion in Florida Google Jeffrey Epstein: Controversies surrounding paedophile billionaire Jeffrey Epstein's island The private Caribbean island, Little St James is part of the US Virgin Islands NBC News Jeffrey Epstein: Controversies surrounding paedophile billionaire Jeffrey Epstein's island The private Caribbean island, Little St James is part of the US Virgin Islands NBC News

The nearly decade-long, multi-jurisdiction case against Epstein highlights the complexities in one of the signature federal laws to come out of a series of horrific child rapes and murders in the 1980s and 1990s — a 1994 federal statute that requires all 50 states to establish sex offender registries and, separately, adopt some form of community reporting on the whereabouts of those who have committed serious sex crimes.

How to set up those registries has been left to each state, whose requirements for sex offenders — and even which lawbreakers are considered eligible for sex offender registries — vary considerably.

States may require registration for just a few years or for life. Some offenders are required to check in every few days if they are homeless, while others must verify their information only twice a year. Failure to comply can be a felony.

“These cost a lot of money and they’re not working for the most part,” said Elizabeth Jeglic, a professor of psychology at John Jay College of Criminal Justice who specialises in sexual violence prevention and has studied sex offender registries.

“It would make everything easier if everything were standardised and the same laws were applied everywhere.”

Florida’s law states that sex offenders cannot live near or work in schools or other places where children congregate.

Residency requirements are so strict there that at one point, the only place sex offenders could live in Miami was under a bridge.

Earlier this year, a federal judge struck down part of Alabama’s law that required those on the registry to carry driver’s licenses or other ID identifying them as sex offenders.

Other states have tried to make the laws more flexible in recent years.

In 2016, Arizona passed a “Romeo and Juliet” exception allowing young people who had relationships with younger people to petition to get off the registry.

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California recently passed a law that would begin to loosen the registration requirement for some offenders, who right now are required to register for life.

New Mexico’s law is one of the more lenient, with no limits on where offenders can live or what jobs they can hold. Offenders can be removed from the registry in 10 years depending on the severity of their crime.

The degree to which Epstein had to report to authorities in that state could be important, since it has emerged that his sprawling Zorro Ranch may have been the site of other crimes.

Earlier this year, Maria Farmer, another woman who has accused Epstein of sexual offences, said in an affidavit that her sister, then 15 years old, was flown by Epstein to the ranch in New Mexico and was touched “inappropriately” on a massage table by him.

This week, the New Mexico attorney general’s office said it has begun its own inquiry into potential crimes in New Mexico.

“We have been in contact and interviewed multiple survivors of alleged abuse here in New Mexico,” Matt Baca, senior counsel for the attorney general’s office, said in an interview.

“At this point it’s our intention to turn over evidence we’ve gathered from those interviews to the feds.”

The fact that Epstein would be required to register as a sex offender has been a crucial point in labour secretary Alexander Acosta’s defence of his role in overseeing the agreement not to prosecute him on federal charges.

But New Mexico authorities determined it would not be necessary in their state.

In making its determination, the New Mexico Department of Public Safety sent Epstein a letter in 2010 informing him it had received notification from Florida authorities that he was a convicted sex offender and that he had to register with the Santa Fe County Sheriff’s Office.

Epstein went with his lawyer to the office, where he initially registered as a sex offender, and notified the authorities whenever he was travelling to New Mexico.

Deborah Anaya, a former detective with the Santa Fe County Sheriff’s Office, made an unannounced visit to Epstein’s ranch that August.

She interviewed him as part of the office’s determination of his sex offender status. She described the estate as “very large, very secluded and very high-security”.

In the questionnaire she completed on Epstein, she said that he was 6 feet tall and 180 pounds, with gray hair.

She made note of his assets associated with the property, including vehicles such as a Hummer H2 and a Chevrolet Suburban, and aircraft including a Boeing 727, a Gulfstream private jet and two helicopters, a Bell 407 and a Sikorsky S-76.

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Less than a month after Ms Anaya questioned Epstein at his ranch, the New Mexico Department of Public Safety sent another letter informing him that he was not required to register as a sex offender with the state.

The determination was made by a team within the state’s sex offender registry unit, which “translated” Epstein’s offence in Florida into New Mexico law, which has different age requirements for registration depending on the specific offence, said Herman Lovato, a spokesperson for the public safety department.

For the offence to which Epstein pleaded guilty, procuring a minor for prostitution, state law provides that registration is required when the victim is 16 or younger.

“It was determined at that time that because the victim was not under the age of 16, Mr Epstein does not have a registration requirement in New Mexico,” Mr Lovato said.

But the age of the victim associated with Epstein’s guilty plea remains murky.

To begin with, dozens of girls as young as 13 told police they had been sexually abused by him.

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Mr Lovato said a Florida police report listed the age of the victim as 17. But the state attorney’s office there has said that the girl was 16, and the Miami Herald reported that the obfuscation of her age was deliberate.

Michael Edmondson, a spokesperson for the current state’s attorney in Palm Beach County in Florida, said he could not provide the age of the victim or any details of the crime to which Epstein pleaded guilty.

Court records are also strangely silent as to the victim’s age.

In the deal Epstein struck with federal and local prosecutors, he agreed to plead guilty to only one count involving a minor: procuring a person under the age of 18 for prostitution.

He also pleaded guilty to solicitation. The indictment did not specify the age of the victim, and her name appears to be redacted.

At the plea hearing, Judge Deborah Dale Pucillo did not go over the specific circumstances of the cases.

At one point, she asked, according to a transcript of the hearing: “Are there more than one victim?”

The prosecutor answered: “There are several.”

Spencer Kuvin, a lawyer who represented three of the girls, including the 14-year-old who he said was the first to come forward, said the hearing was highly unusual because it did not establish a factual basis for the guilty plea, and Epstein’s lawyers may have had leeway to select which victim — of which age — about whom their client made admissions.

“His attorneys would have negotiated who they were going to pick that was in a list of girls that they had,” Mr Kuvin said.

“I would want to choose, if I represented someone like him, the oldest possible girl within the statutory framework, and that way he would be excluded from having to report in certain states.”