WEST COVINA, Calif. — After a boozy Saturday night, Sarah Maguire awoke the next morning to find that her iPhone was gone. Her roommate’s phone was gone, too. Were the phones at the bar, she wondered, or in the cab?
Using the Find My iPhone app on her computer, she found that someone had taken the phones to a home in this Los Angeles exurb, 30 miles east of her West Hollywood apartment.
So Maguire, a slight, 26-year-old yoga instructor, did what a growing number of phone theft victims have done: She went to confront the thieves — and, to her surprise, got the phones back.
“When I told my mom what I did, she thought I was crazy,” Maguire said.
With smartphone theft rampant, apps like Find My iPhone offer a new option for those desperate to recover their devices, allowing victims like Maguire to act when the police will not.
But the emergence of this kind of do-it-yourself justice — an unintended result of the proliferation of GPS tracking apps — has stirred worries among law enforcement officials that people are putting themselves in danger, taking disproportionate risks for the sake of an easily replaced item.
“This is a new phenomenon — it’s not simply running after the person to grab the phone,” said George Gascón, the San Francisco district attorney and a former police chief. “It opens up the opportunity for people to take the law into their own hands, and they can get themselves into really deep water if they go to a location where they shouldn’t go.”
“Some have been successful,” Gascón said. “Others have gotten hurt.”
Smartphones have become irresistibly delectable morsels for thieves. More than 3 million were stolen last year, according to a survey by Consumer Reports.
Since 2011, cellphone thefts have risen more than 26 percent in Los Angeles; robberies involving phones were up 23 percent in San Francisco just last year. In New York City, more than 18 percent of all grand larcenies last year involved Apple products.
Victims are often desperate to recover their stolen phones, which, as home to their texts, photos, and friends’ phone numbers, can feel less like devices than like extensions of their hands. While iPhones may be the most popular with thieves, apps that can track stolen phones using GPS are now available for most smartphones.
And although pursuing a thief can occasionally end in triumph, it can also lead to violence, particularly because some people arm themselves — hammers are popular — while hunting for their stolen phones.
In San Diego, a construction worker who said his iPhone had been stolen at a reggae concert chased the pilferer and wound up in a fistfight on the beach that a police officer had to break up. A New Jersey man ended up in custody after he used GPS technology to track his lost iPhone and attacked the wrong man, mistaking him for the thief.
Even an off-duty Los Angeles police detective pursued his son’s phone, which had been stolen at a soccer game. The officer, who asked that his name not be used for fear that civilians would follow his example, and his son used GPS to track the phone leaving the field.
They got in the car and followed it — first to a mall, then to a nearby home. The officer knocked on the door, and then his son called the phone, which went off inside the bag of the boy who had taken it from the field.
The officer urged anyone whose phone is stolen to call the police, noting that he had had three other off-duty officers with him.
“What if these were gang members?” he said. “Somebody can get killed doing this.”
Commander Andrew Smith, a spokesman for the Los Angeles Police Department, called the trend “a big concern.”
“It’s just a phone — it’s not worth losing your life over,” he said. “Let police officers take care of it. We have backup, guns, radio, jackets — all that stuff civilians don’t have.”
Still, although police departments have devoted more resources to combating smartphone theft, most cannot chase after every stolen device right away, especially if the phone was left idly on a bar rather than seized in an armed robbery.
And despite the obvious risks, the lost phone’s location — blinking on a GPS app — is a siren song many find too alluring to ignore.
Police chiefs have advocated another solution that they say could end smartphone thefts: a mandatory “kill switch” that would render stolen phones inoperable and therefore unattractive to thieves.
“This would all be moot if we had an industrywide kill switch,” Gascón said.