The burglars come out at daylight.
When the residents of South Boston are at work, thieves slip in to their homes, jimmying weak locks with sheet metal or credit cards, and sneak off with jewelry, iPods, laptops, and flat-screen televisions.
No one seems to notice them. No one knows what they look like.
Police, who have been trying to nab the burglars for months, said they are flummoxed.
"We're a little frustrated, because we've done all the investigative things we thought would help," Sergeant Detective Kevin Finn said yesterday. "We've put in a lot of man-hours but we just can't get that break."
Police in South Boston are now calling on residents to be vigilant and report any strange cars or people they see in their neighborhoods.
If they see a car double-parked or a van idling outside a house, they should write down the license plate and call police, investigators said.
"Someone in the neighborhood has to see something," Finn said. "There more than likely has to be a vehicle outside when they're stealing these [belongings] that they're bringing into the vehicle."
Between September and February, 120 break-ins were reported, compared with 71 for the same period the year before, police said.
Few of the burglaries show any sign of forced entry. In most cases, the front door had been left open or the locks were weak, police said, urging landlords and homeowners to install deadbolts.
The burglars have struck all floors of the low-rise brick apartment buildings and freshly painted houses that dot South Boston, historically a working-class neighborhood of families that in recent years has seen an influx of young professionals moving into refurbished and newly built condos.
The changing character might be helping the thieves stay under the radar, Finn said.
"Obviously there aren't as many stay-at-home mothers that are just home during the day and making observations,' he said. "When I grew up, everyone knew what was going on, because there were more eyes on the street."
The closest officers came to catching a suspect was Wednesday at about 1:50 p.m., when a dog walker came into an apartment and found a young man who appeared to be 17.
The teenager, who was 5 foot 7 and wore a North Face jacket and a black baseball hat emblazoned with a white B, ran out the back door and fled down East 7th Street, police said. Nothing was missing from the home.
Residents around South Boston said they were startled to learn of the break-ins.
Courtney Cotta, a 31-year-old high school teacher, said that she recently received a flier from her neighborhood association warning about the jump in burglaries.
"To me it's sort of one thing you have to put up with living in the city," she said. "But it is disturbing."
Maria Cramer can be reached at mcramer@globe.com.
