E.Torres mailed a package from Washington to Denver. The contents of the package were worth only $12, so Torres didn't but insurance. When the package failed to arrive, Torres asked the United States Postal Service to investigate.

Two weeks later, USPS gave Torres the result of its investigation: The intended recipient says he didn't receive the package.

"I told them that much when I filed the complaint," Torres pointed out. Now he raises these questions:

Is this all USPS does? Just what does an investigation consist of? How can a parcel get lost between one post office and another? Should I give up on this parcel, or do lost parcels sometimes turn up later?

To get the answers, I called USPS Consumer Advocate Tom Chadwick, who is one of the best problem solvers in Washington - in or out of the government.

Tom told me that USPS does do more than verify that the package wasn't received. It also checks its dead parcel office.

A parcel may be in the dead parcel office because an error in its address made it undeliverable. The intended recipient may have moved without leaving a forwarding address. The package may have been damaged by USPS machines or personnel, and as a result the address label may have become separated from the remainder of the package. More often, the fault lies with the sender: his parcel wasn't made to withstand the rigors of travel.

"When a package is insured or registered," Chadwick told me, "at least we have a couple of pieces of paper as clues. We have some numbers we can check. But when the lost package has been sent by ordinary parcel post, our best hope is to find it in the dead parcel office.

"This is more complicated than you might think because so many of the parcels we can't deliver contain common items of such small value they are not insured.

"When we can start our investigation with a piece of paper and a number, we do pretty well. For example, not too long ago a lcoal brokerage firm sent a customer $32,000 in negotiable securities by certified mail.The slip recipient was supposed to sign came loose from the envelope and was found 'loose in the mails,' so it was returned to the brokerage firm - where it was immediately noticed that the customer hadn't signed it.

"The broker called his customer and asked whether the customer had received the securities. When the customer said he hadn't, the broker became alarmed and called us. We located the securities with no trouble at all."

Are thefts a factor in causing parcels to become "lost"? Yes, but not a significant factor, says Chadwick, who considers the USPS security people "the best police force in the world." He says, "Every so often, some clever fellow thinks he has worked out a foolproof system for stealing, but it doesn't take postal inspectors very long to catch most of these people and put them in jail. These days, our biggest problem isn't theft inside the system but schemes on the outside that use USPS for delivery."

What in the world does that mean? "Things like the manipulation of computer-generated labels that deliver goods to people who aren't supposed to get them."

Do lost letters and parcels sometimes turn up many months later? Yes, indeed. They lie hidden in "presumably empty" equipment after the Christmas rush and don't turn up until the equipment is needed again, perhaps the following Christmas. "We just found an entire hamper of letters that had been mailed last December," Chadwick said. "The hamper had been in dead storage all this time. The same thing happens with presumably empty mail sacks. We try to guard against these goofs, but when you handle billions of pieces of mail, you can't be perfect."

Now that I don't understand. I never make mistakes.