Not long ago, when Mr. Staser suspected someone had been stealing, he held the culprit with a Taser at a store’s front door until the police arrived. He said he once followed another man on foot for about 45 minutes, trying to talk to him about issues of “accountability for his actions,” even though the stolen goods, valued at about $1,500, had been dropped at the store’s door. Mr. Staser only ended his pursuit after the man desperately waved a $20 bill at a passing motorist, climbed into the car and raced off.

Mr. Staser said he knows that he might one day cross a line and put himself at risk. The culprits are almost all much younger than he is, for one thing.

“I’ve got to stop chasing these guys,” he said, shaking his head.

Anchorage, a city with nearly 300,000 residents, has long had its share of rough edges, including patterns of homelessness and transience, with people here for a while, then gone. In interviews around the city, people said they still felt safe walking around, day or night, but the need to lock doors — a new imperative here — has left them unsettled.

Anchorage set a record for homicides last year, with 35, though violent crimes overall were up only slightly, according to the F.B.I. Some other American cities have far higher per capita rates of killings, but Alaskans say the uptick in property crime is still palpable.

The Anchorage Police Department says auto thefts jumped by 52 percent in 2017 over the previous year. In the first two months of 2018, the numbers were up again — 27 percent over the same period last year. The city went from having the nation’s 47th highest rate of auto theft per capita in 2015 to the sixth highest in 2016, according to the National Insurance Crime Bureau, an insurance industry-funded group.

Some people here attribute the rising crime to an increase in opioid addiction and an economic downturn. The state’s unemployment rate, 7.3 percent in February, was the highest in the nation, as the state’s oil industry has sputtered. The State Legislature also overhauled the criminal justice system in 2016, reducing penalties for some property crimes.

“There isn’t just one thing,” Justin Doll, the Anchorage police chief, said. Chief Doll said that new hires have brought the department to its highest staffing ever, with 435 officers, giving him hope that the crime trend can change. Arrests for car theft have also increased, he said, adding: “To me that suggests we’re starting to have an impact.”