Identity thieves aren't necessarily using the internet to perpetrate their crimes — in fact, most are sticking to low-tech methods such as stealing letters from traditional mailboxes, according to a new study.

Only about 20 per cent of the 517 identity theft cases closed by the U.S. Secret Service between 2000 and 2006 involved the internet, the study by the U.S. Center for Identity Management and Information Protection found.

Most perpetrators favoured non-technological methods, such as rerouting mail through change-of-address cards and digging through dumpsters.

The study found also that most offenders were young — about 42.5 per cent were 25 to 34 years old, with a further 18 per cent aged 18 to 24. About two-thirds were male, while nearly a quarter were born outside the United States.

About 80 per cent of cases involved the offender working by him or herself or with a single partner.

Victims didn't know the perpetrators in most of the crimes, while only about one-third were "inside jobs" by employees of a business. Of those crimes perpetrated by employees of a business, about 40 per cent were in the retail sector. The report considered stores, gas stations, car dealerships, casinos, restaurants, doctors' offices and hospitals as retail operations.

Only about one-third of cases happened in situations where the offender stole inside information from his or her own business.

The report was funded by the U.S. Department of Justice and was to be released at a news conference in Washington on Monday.