CAMDEN — Police in one of the nation’s most crime-ridden cities are sending warning letters to the owners of cars caught on camera at one of the city’s many drug hot spots.

The effort in Camden is an attempt to curtail drug activity and perhaps solve some crimes in a time when the department’s technology is improving but police staffing is down. The hope is that the warning will have an effect, because arrests are so hard to make, and it’s a tactic police say they’ve never heard of being tried anywhere else.

The police department and the Camden County Prosecutor’s Office say they have been having officers monitor the camera posted at the North Camden intersection of Sixth and York streets, a place surrounded by vacant lots and known for heroin. Checking it no more than a few hours a day, they’ve been able to make out license plate numbers during of 624 different vehicles during apparent drug deals since the beginning of the year.

Police say that 90 percent of the cars are registered in places other than Camden — more evidence of what city officials in a city that also ranks as one of the nation’s most impoverished have long believed: Camden may be plagued by drug-dealing, but much of the demand comes from the suburbs.

“This problem is not Camden’s problem,” said Prosecutor Warren Faulk. “It’s society’s problem.”

On Faulk’s way to work in Camden from suburban Cherry Hill, he said he often sees drivers heading to drug corners. “We know that at 8 o’clock in the morning, there is no legitimate purpose for someone from Cherry Hill going to North Camden,” he said. “You’re not going to your doctor. You’re not going to visit your grandmother.”

Next week, those 624 vehicle owners — including 205 who were identified as repeat customers — will get letters telling them that they face legal consequences if they keep coming to the city for drugs.

The letters are topped with “WARNING” in red. The letters threaten that the cars’ occupants could face arrest, and the cars themselves could be forfeited.

Camden Police Chief Scott Thomson says he hopes the letters cause some angst, that parents and spouses of the drug buyers take it a sign to get their loved ones help — or just to deter the buyers.

“If the letter scares you,” he said, “so be it.”

He also said he’ll share the information about which cars stop at drug corners with suburban police officials. He said they might be able to use it to help identify culprits in crimes like thefts and burglaries that addicts often commit to raise money to pay for drugs.

“It’s good police work, is what it is,” Thomson said.

So far the effort, “Operation Drug Net,” has been running at only Sixth and York, but police say they’ll expand it to other spots. They believe there are 175 outdoor drug markets in the city — including many at the heart of the most violent areas. Police have cameras at 81 spots in the city of under 80,000.

While the warnings may be stern, Thomson and Faulk say they don’t have enough officers to identify and track down the buyers. That kind of investigative work has become even more challenging since nearly half the city’s officers were laid off a year ago. While many have been hired back, the number of officers is still down.

Even with plenty of officers, busting drug deals in action has always been a problem for police because they can be done in just a few seconds.

The men and women near Sixth and York on Friday didn’t seem especially worried about the new police tactic hurting business. Though they declined to give their names or elaborate, their actions told why: When a car approached, a few people pointed for a spot for it to park just outside the overhead camera’s scope. One woman asked a reporter: “Are you going to buy something?”

Meanwhile, another group of people a half block down hurled some rocks toward the reporter’s car.