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The thwarted bomb plot at a Chicago-area mall — news of which broke Friday with the arrest of a man armed with grenades and plans to use them — is likely to trigger holiday shoppers' worst fears about their safety as they brave crowds and troll for gifts.

But malls and the security companies that protect them are ratcheting up efforts to prevent a successful attack at the busiest season of the year — posting more security officers, working with police, installing more cameras and even putting up observation towers in parking lots.

"At this time of year, malls always step up security if for nothing else simply for the rash of thefts that could occur," said John Cutter, president of Beau Dietl & Associates security firm and the former chief of the intelligence division of the New York City Police Department.

"In light of the recent arrest and any intelligence information that has come out in reference to malls, I'm sure the local police departments in various cities are stepping up their presence."

In fact, most shopping centers will subcontract with law enforcement to supplement the security provided to them by private firms because guards generally aren't allowed to carry weapons or detain suspects.

Mall security guards are used "as a deterrent, but the law enforcement is there with arrest powers and firearms," said Robert Burns, a senior vice president for Wackenhut Corp., a major national security company whose clients include shopping centers.

Protection of sprawling retail facilities with large parking lots is often shored up with the help of observation towers fitted with security cameras that can increase the range of view of the rest of the CC-TV system. It might also dissuade would-be criminals.

"People see them. It's an additional deterrent," Burns said. "More and more patrons visit during the holidays, and you can increase your visibility to the far sides of parking areas."

But those systems are costly — Cutter said they run about $150,000 per unit — so many malls probably wouldn't invest in that technology since their existing camera systems tend to cover the inside and outside of the premises.

More common, however, is to post officers and guards in mobile towers that are sprinkled throughout parking lots. Typically, they're outfitted with two-person offices, according to Burns.

Roving patrols — vehicles with amber lights that scout parking lots — are also increased during the holiday shopping season, according to Cutter.

Malls are a special challenge for security details because of the "free and open way you can access" them, he said. "You can freely walk through and have a bubble jacket or a knapsack on."

Guards and officers stationed at shopping centers are generally trained to look for anything out of the ordinary: packages left unattended, vehicles parked near entrances, people dressed inappropriately for the season and patrons who are acting jittery or exhibiting other abnormal behavior.

"In light of the recent arrest, I'm sure they've refreshed everybody's memory about what they should be looking for," said Cutter.

Cutter and Burns said profiling is typically not used by mall security unless they're looking for a particular wanted suspect or a perpetrator who has been previously caught committing a criminal act at the mall. What officers are on the hunt for, they said, is suspicious activity.

"They look for indicators," Cutter said. "It doesn't have to do with a person's race or religion — it has to do with physical characteristics. Are they dressed unusually for the time of year? Are they acting nervous? Are they doing things indicative of somebody not necessarily interested in being in the mall for shopping but for other reasons?"

The largest mall in the United States said security has long been a primary focus.

"The safety and security of our shoppers, tenants and employees has always been our top priority, and it continues to be," said Dan Jasper, spokesman for the Mall of America in Bloomington, Minn.

Thankfully, experts don't predict we'll ever see the day when customers will have to go through metal detectors and have their bags checked as they enter a mall or shopping center.

"I doubt it's going to happen here," said Cutter. "It's a free society, and I think we want to keep it that way as much as we possibly can. The best weapons we have are people's eyes and ears. The more eyes you have looking for [a suspect], the more likely you'll find him."