Gazing into the crystal ball for profit is illegal in Philadelphia, but the city couldn't stop it.

In June, a psychic offered information in the case of Lisa Stebic, a 37-year-old mother of two missing since April 30. The psychic claimed that Stebic would be found in Silver Springs State Park. The family endured a “roller coaster” of emotions as police and volunteers searched the park for Stebic’s remains.

At first, it appeared that the psychic was right; bones were eventually found in the park. Sadly, the bones were of native deer, not a woman.

Once again, the Stebic family’s hopes for closure were raised—then shattered—by a psychic’s false information. Several other “psychics” also offered incorrect and contradictory information; Stebic remains missing.

The same thing happened in the search for Madeleine McCann. The four-year-old British girl disappeared May 4 while at a resort in Portugal. A psychic had directed police to search an area where she would be found; the police checked but returned empty-handed. There was no sign of the missing toddler. These situations are all too common in missing persons cases; despite claims from self-promoting psychics, there has never been a case of psychic information leading police to a missing person.

In one of the worst errors, “psychic” Sylvia Browne, a regular on the "Montel Williams" show, told the parents of missing teenager Shawn Hornbeck in 2003 that their child had been kidnapped by a dark-skinned man with dreadlocks, and that Shawn was dead. In fact, Hornbeck was found very much alive in January 2007; his abductor had neither dark skin nor dreadlocks.

There are many instances of psychics contacting the families of missing children and offering their services for a fee. The parents are usually so desperate for news that they willingly pay, even if they are skeptical.

Even those psychics who do not exploit the bereaved for monetary gain are still hurting instead of helping. Aside from falsely raising the family’s hopes, psychic tipsters waste valuable police time and resources following up on their information.

Anyone who follows the news regularly can see for themselves whether psychics have the powers they claim. Simply follow the next high-profile missing person case and see if and how the person is eventually recovered. Did psychic information lead police to the person? Did police find him or her through routine policework? Or, more likely, did a passerby find the body in some out-of-the-way area weeks or months later?

People should also ask themselves some simple questions when they hear psychics’ claims. If psychics can really find missing people, why aren’t they in Iraq, rescuing kidnapped hostages? Why haven’t psychics caught serial killers before they kill again? Why do different psychics give contradictory information? Why do we need Amber Alerts to find kidnapped children? And where are Osama bin Laden, Natalee Holloway, Lisa Stebic, Madeleine McCann, and the thousands of other people whom searchers are desperate to find? On these questions, psychics are as silent as the missing persons they fail to find.

Benjamin Radford investigates and writes about “unexplained” phenomenon for the non-profit Committee for Skeptical Inquiry. He is author or co-author of three books, including “Media Mythmakers: How Journalists, Activists, and Advertisers Mislead Us.” This and other books are available on his website. He shares his skepticism regularly on LiveScience.