There is honour among certain thieves.
The professional thief is one who steals professionally. This means, first, that he makes a regular business of stealing. He devotes his entire working time and energy to larceny and may steal three hundred and sixty-five days a year. Second, every act is carefully planned. The selection of spots, securing of the property, making a get-away, disposing of the stolen property, and fixing cases in which he may be pinched (arrested) are all carefully planned. Third, the professional thief has technical skills and methods which are different from those of other professional criminals. Manual skill is important in some of the rackets, but the most important thing in all the rackets is the ability to manipulate people. The thief depends on his approach, front, wits, and in many instances his talking ability. The professional burglar or stickup man (robber with a gun), on the other hand, uses violence or threat of violence even though he may on occasion use soothing language in order to quiet people. Fourth, the professional thief is generally migratory and may work in all the cities of the United States. He generally uses a particular city as headquarters, and, when two professional thieves first meet, the question is always asked: “Where are you out of?”
In addition to these four characteristics, professional thieves have many things in common. They have acquaintances, congeniality, sympathy, understandings, agreements, rules, codes of behavior, and language in common. p. 4
The attitude of one thief toward another or of one group of thieves toward another group is very friendly unless there is some personal enmity existing between them aside from their professional activities. Even though personal enmity existed, one mob (group of thieves who work together) would advise the other, directly or through a third party, of any imminent danger. Regardless of how strong the ill feeling be between two thieves, neither of them would want to see the other pinched, and each would exert much effort to prevent it. p. 5
Thieves also give much assistance to other thieves who are in trouble. Personal feelings seldom affect this. Jew Jake, a booster, had for years been bad friends with Little Eddie, another booster. Jake got in the can in Chicago, where he was a stranger and was broke. Eddie heard of it and approached a person who knew the fixer and asked him to find out how much it would cost to get Jake out. The fixer announced $150 as the amount necessary. Eddie turned over the $150 with the statement: “I hate the no-good bastard, but I can’t let him lay in the can for $150.” p. 7
Codes of ethics are much more binding among thieves than among legitimate commercial firms. Should an outfit have a putup touch (opportunity to theft suggested by an outsider) for 10 per cent, no other outfit would think of offering the putup man 15 per cent for it, although no commercial house would hesitate to outbid a competitor in a case like this. p. 9
This is the importance of keeping secrets even in the most absurd situations:
It is understood that no thief must squawk (inform) on another. The instances where professional thieves have squawked are so rare that no serious consideration of this angle is necessary. Prisoners squawk for one purpose only – to relieve themselves of punishment. Professional thieves have no thought of receiving punishment while in the hands of the fix, and they have no incentive to squawk. Police officials, prosecutors, and others rarely question professional thieves. They have or else haven’t got a rap [criminal charge] for the prisoner. In either case there is no gain from questioning. If a thief should squawk, the other thieves would not descend to the same plane and squawk on him. They use much better methods. The worst penalty is to keep him broke. This is done by spreading he news that he has squawked, which makes it impossible for him to get into any mob. That is the greatest disgrace and the greatest hardship that can befall a thief. p. 11
– The Professional Thief: An astonishing revelation of criminal life, by a professional thief, Annotated and Interpreted by Edwin H. Sutherland, The University of Chicago, 1937.