Phoenix- The caller to the Phoenix-area Taco Bell said he was a police officer and informed the manager there was a thief on the premises. Someone’s pocketbook was missing, the caller said, ordering that a female customer be detained and strip searched in a back office.

But there was no theft. Investigators believe the caller was an impersonator, possibly from north Florida, who has pulled the same stunt dozens of times nationwide since 1999 with alarming success.

The caller, who sometimes poses as a company official, has persuaded managers at restaurants and other stores to detain and search employees for drugs or money. Targets have included Taco Bell, McDonald’s, Wendy’s, Burger King, Ruby Tuesday, Applebee’s, Perkins and others.

The caller’s motive is unknown. Because his targets are primarily restaurants, one theory is that he is a disgruntled former fast-food worker. Some investigators believe he may be a sexual deviant who enjoys exercising power over people.

The searches have included male and female victims. Some businesses have been sued, and some managers have faced criminal charges.

“It’s a terrible scam, and we feel badly for everyone who was involved,” said Bob Bertini, a spokesman for Wendy’s International, referring to incidents at four Boston-area Wendy’s outlets in February. “The people who were caught up in this scam thought they were responding to direct orders from the police, and the caller in this situation can be very convincing and persuasive.”

Authorities believe the hoaxer is one male suspect who uses a phone card. Some calls have been traced to a public telephone in Panama City, Fla. Police there are investigating, but spokesman Sgt. Kevin Miller refused to discuss details.

The March 22 call to the Taco Bell in Fountain Hills, Ariz., is believed to be the first time a customer has been the victim.

In that case, the Taco Bell manager pulled aside a 17-year-old girl who roughly matched a description provided by the caller, Maricopa County Sheriff Joseph Arpaio said. Told she would go to jail otherwise, the girl submitted to the search as the caller remained on the line to direct it.

The manager is on administrative leave while the sheriff’s office investigates, Taco Bell spokeswoman Laurie Schalow said.

In Massachusetts, the caller could be charged with rape for one of the Wendy’s incidents, said Sgt. Victor Flaherty of the West Bridgewater police, explaining that the rape statute allows charges to be filed against someone for just directing such an act.

Flaherty said that the managers in the local cases will not face criminal charges because police “felt they were victims, too.”

But Arpaio said he thinks managers are “ignorant” to fall for the scam and should face criminal charges if warranted. He said investigators are considering whether to charge the manager in the Taco Bell case.

“It’s mind-boggling,” he said. “How can a responsible person in this world ever do what has been occurring just because some guy calls them on telephone and tells them he’s a cop?”

Indeed, a former Hardee’s assistant manager in Rapid City, S.D., was charged with kidnapping and second-degree rape after he allegedly detained and forced a female employee to strip at a caller’s urging in June. He was acquitted. The man’s attorney said he was the victim of a “freak who plays God.”

And a Burger King manager in Odessa, Texas, was charged with illegal restraint and fined $500 for forcing a woman to strip at the direction of the caller.

“Restaurant unit managers are about the smartest and normally the most cautious and street-wise professionals in all of food service,” said Milford Prewitt, national affairs editor for the industry newspaper Nation’s Restaurant News. “Why they are falling for this is about the most amazing thing I’ve ever seen.”

But Craig Annunziata, a Chicago attorney who has defended about 20 fast-food franchisees against hoax-related lawsuits, said it’s human nature for the managers to want to help when they become convinced there’s a police officer or superior on the line.

Because the incidents have been so varied and embarrassed restaurant officials are often reluctant to publicize them, police agencies didn’t note the connection until the past year or so.

“It has taken this long for the pieces of the puzzle to come together and for people to start comparing notes and realizing the scope of the problem,” said Terrie Dort, executive director of the National Food Service Security Council, an organization of chain-restaurant security officials.

Dan Jablonski, a former FBI agent who now operates a private investigative firm in Wichita, Kan., has been looking into the incidents since he was hired last year by a major fast-food chain, which he declined to name.

Jablonski said he’s documented about 70 of the hoax calls through lawsuits, newspaper reports and police, and he figures there are more.

“This guy is a sexual deviant who in fact got his thrill initially,” Jablonski said. “But as time went on, it grew more into a power and control type of thing, where he gets great pleasure out of manipulating people, convincing them to take other people’s clothes off.”