One month after a New Jersey lawyer was shot and killed during a botched carjacking at the Mall at Short Hills, police are investigating another Short Hills car theft.

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No one was injured when thieves stole a Porsche out of a homeowner's driveway.

Authorities say carjackings are on the rise in many communities across the state, and frequently those responsible are not apprehended, nor is the vehicle recovered.

County College of Morris criminology professor Nick Irons said this is not surprising because the carjackers usually act very quickly.

"Once they get the car, they probably take it to a chop shop where they'll reduce it down to mere parts, or they'll ship it overseas and sell it that way," Irons said. "They'll simply ship it overseas to a Third World country, where they can just get a title for it and get it down the road at a very good price."

The professor also said stealing a car simply for fun could be another possibility.

"They'll even just take out on the street and use it for joyriding, pass it off to their friends, that's another thing that they'll do," Irons said.

According to Irons, some of the parts that are removed from stolen cars are more valuable than the automobile itself, including airbags, the wheels, the tires, and the radio equipment inside the car.

So what's the best way to avoid being carjacked yourself?

"I would buy an inexpensive car if I were going to drive it to the mall," Irons said. "I wouldn't want to take something fancy."

And if you are confronted by carjackers, the professor has some simple advice.

"Let them take the car," he said. "A car is not worth a person's life."