By Chris Summers BBC News Online

For five years Frank Abagnale lived out many young men's fantasy.

The only thing I did which would actually be more difficult today, after 9/11, is posing as an aircraft pilot Frank Abagnale

He posed as an airline pilot, a doctor and a lawyer, spent $500,000 on clothes, hotels and meals in fancy restaurants and defrauded banks of another $2m, which was later found in cash deposit boxes.

Much of his bogus income and status was used for chasing and charming beautiful women.

But eventually the authorities caught up with him and, still only 21, he spent almost five years in French, Swedish and US jails.

Abagnale (pronounced Abignail) went on to become one of the world's most respected experts on identity and cheque fraud.

Nowadays, aged 54, he lectures at the FBI Academy in Quantico, Virginia and says more than 14,000 financial institutions, corporations and law enforcement agencies have adopted his fraud prevention programmes.

Frank Abagnale has spent 25 years advising the FBI

He told BBC News Online: "The only thing I did which would actually be more difficult today, after 9/11, is posing as an aircraft pilot.

"Becoming a doctor and a lawyer and forging the qualifications needed is easy and forging cheques is definitely easier."

He added: "I consider my past immoral, unethical and illegal. It is something I am not proud of."

Abagnale's extraordinary life is portrayed in Steven Spielberg's latest movie, Catch Me If You Can, which opens in the UK on Friday.

Myths about Frank Abagnale

He is an only child His father was a conman He wrote bad cheques worth $10m (it was $2.5m) He was on FBI's Ten Most Wanted List He rang the FBI and taunted its agents He married a girl called Brenda while on the run but had to flee from the wedding reception

The film superbly captures the feel of the late 1960s and early 1970s, an age when many people in America retained an innocence and naivet� from earlier times.

DiCaprio, 28, plays young Frank, who spent two years posing as a Pan-Am pilot so he could fly for free all over the world.

Fortunately for the passengers, the teenager was not actually flying the planes.

Artistic licence

Tom Hanks plays an FBI agent on the trial of the youngster.

His character, Carl Hanratty, was invented with some artistic licence by Spielberg's screenwriter Jeff Nathanson to help with the narrative.

Hanratty is an amalgam of FBI agent Joe Shea, who worked on the case, and Abagnale's parole officer.

Shea, now 83, is still a friend and has seen Abagnale mature and his children grow up.

Nathanson's script was based on Abagnale's own book, which was co-written by journalist Stan Redding, who "dramatised and exaggerated" some of the events.

The film rights were sold in 1980 but it was only when Spielberg's Dreamworks company bought them that the movie got made.

Nathanson's script hints at Abagnale's loneliness and suggests he was not a spoilt brat on a criminal caper but was struggling to cope with the pain of his parents' divorce.

When Abagnale was eventually caught he was sentenced to 12 years jail in the US, but took up his legitimate career helping companies fight fraud when he was released.

DiCaprio, seen here in Gangs of New York, is having a busy year

Fifteen years ago his company paid off the debts he had accrued during his criminal career.

Abagnale, a father-of-three who lives just outside Tulsa, Oklahoma, looks back on his early criminal career with the benefit of hindsight.

He says he took advantage of the naivet� of the 1960s, when people would just believe you were a pilot just because you turned up in a pilot's uniform.

Charm

He also exploited numerous loopholes in bank security and used his charm to persuade cashiers to bend the rules.

Much has changed in the last 30 years.

Americans write 50 billion cheques a year

While new computer technology has made bank cheques, airline identity cards and medical certificates arguably easier to forge, the introduction of the cheque guarantee card has worked against conmen.

Most corporations also have systems in place to combat such security breaches. Ironically it was Abagnale, the classic poacher turned gamekeeper, who invented many of these systems.

An FBI spokesman told BBC News Online the FBI had not been involved in the making of the film and it was not therefore historically accurate.

But he said: "Like all movies, people should view them for what they are - entertainment."