Frank Sinatra narrowly escaped arrest as a Mafia courier, according to an unauthorised biography of the singer.
Sinatra is alleged to have been carrying $3.5m in cash
Authors Anthony Summers and Robbyn Swan claim entertainer Jerry Lewis told them the late entertainer "volunteered to be a messenger" for the mob.
"He almost got caught once... in New York," Lewis is quoted as saying. If he had been arrested, he continues, "we would never have heard of him again".
Sinatra, who died in 1998, denied any connection with organised crime.
However, FBI files released after his death portrayed him as a close friend of reputed Chicago mob boss Sam Giancana.
The documents also suggested he had contact with mobster Lucky Luciano during a 1947 trip to Cuba and that his early singing career was backed by New Jersey racketeer Willie Moretti.
Lewis is quoted as saying that Sinatra went through customs with a briefcase containing "three and a half million [dollars] in fifties".
Customs officials reportedly opened the case but aborted their search.
Excerpts of the book in Vanity Fair magazine make it clear that Lewis did not witness the incident in question, but related the account "as a fact of which he had knowledge".
Sinatra is generally thought to have inspired the Johnny Fontaine character in The Godfather, a singer who uses his Mafia connections to advance his career.