If you get a telephone call from a mortgage broker, offering you a "secure 15 percent investment backed by real estate," hang up. Especially if the land is in Arizona or Nevada.

In theory, you are being offered someone else's mortgage. You will lend money to someone who is buying property (but who can't get a loan at a bank). That person will pay high interest for your money, and repay the loan in a lump sum within three to five years. If the borrower defaults, you can foreclose on the property, sell it and get your money back.

At least, that's how it's supposed to work. But it often doesn't -- because some mortgage brokers take your cash but do not invest it in secure mortgages, as promised.

Mary Short, Arizona's banking commissioner, calls the spread of questionable mortgage brokers "a plague" in her part of the country. There are more than 900 brokers in her state, many of them soliciting out-of-state investors. And she doesn't see that there is enough property to go around.

Based on the legal record, it seems she's right. Brokers in several states are being pursued by state officials, alleging such trespasses as soliciting money but not actually investing it in mortgages; diverting investor funds into their own accounts; even running Ponzi schemes, whereby money from new investors was used to pay apparent "high yields" to older investors for as long as the scheme stayed afloat.

Why would investors send their money to a distant state, based on little more than a telephone call and a sales brochure? Because people trust real estate as an investment. They're attracted by the promised high yields. They don't want to be bothered with the difficult job of evaluating investment risk. They don't know what documents to ask for and don't want to pay a lawyer for help.

These brokers also are trapping local investors, who think they know the area but won't take the time to bore into the deal they're offered.

One company now in receivership: Arizona's Metro Home Loans. Roy Scheutze, supervisor of the state's banking and trust division, told my associate Virginia Wilson that its troubles came to light after its owner, H. Keith Rust, was found slain in Phoenix last fall.

Scheutze alleges that in Metro's last year, mortgage investors were promised yields of 16 percent to 18 percent. But much of the money was diverted into Rust's construction business and the receiver will not have enough money to repay all of Metro's investors, according to Scheutze.

Just last month, Arizona officials obtained a temporary restraining order freezing the assets of Action Home Loans. Court documents allege that AHL has been raising money, "supposedly for the purpose of funding loans secured by real property," but wasn't handling the money properly. Some of it, they say, was used to pay expenses; some was commingled with the accounts of other businesses controlled by Action's president. The state banking department found a shortage in the trust accounts that were supposed to be keeping investors' money safe. (Action's lawyer did not return my phone call.)

Missouri recently got an indictment against Creative Funding, a $20 million to $30 million loan broker. It advertised investment returns of 12 percent to 13 percent, according to John Perkins, the state's commissioner of securities. In fact, the indictment alleges that the "borrowers" were apt to be fronts for Creative Funding itself, which used the money for its own purposes. The lawyer for Creative Funding's Malcolm Green said that neither he nor his client would make a statement because the firm is under indictment.

Perkins describes the alleged action as the biggest securities fraud in the state of Missouri. His office is also in the process of seeking an indictment against a mortgage broker in St. Louis who, he says, convinces low-income homeowners to take out mortgages they can't afford. The broker then sells those mortgages to investors. The investors often find they have to foreclose, Perkins said.

A Nevada mortgage broker called Lemons & Associates attracted 3,800 investors with promises of interest rates as high as 18 percent before its collapse, Nevada officials said. The Reno police have the company under investigation. (John Lemons failed to return a phone call.)

In Arizona, the banking department is supposed to keep track of the mortgage-broker industry to keep it clean. But he has three examiners to cover 900 brokers -- so investors can't realistically expect much official protection, from Arizona or any other state. You simply have to look out for yourself.