The number of house break-ins spiked over the last two months across Sonoma County, amid historically low crime rates on a downward trend for the last 20 years.
Local police and the Sonoma County Sheriff's Office have responded by stepping up patrols, warning residents to lock windows and doors, and investigating people with prior habits of committing property crimes.
Detectives have tied at least some of the apparent burglary sprees to individuals or groups.
"Property crimes are up all over the Bay Area," Petaluma Police Lt. Tim Lyons said.
The trend appeared most strong in Petaluma, where the rate of residential break-ins has just about doubled since June, compared to the first five months of the year, according to figures provided by Petaluma police.
Officers have investigated 18 residential burglaries between June 1 and July 24, Lyons said. Between January and the end of May, they took 28 reports.
In one case, a man ran out of a house as a resident came home, and in his flight a baseball cap flew off his head, leaving behind a clue for detectives, Lyons said.
On another day, a Petaluma woman returned to her Draco Drive home after work and was confronted by a woman she didn't know in her house.
"As she put the key in the lock, she heard the deadbolt unlatch," Lyons said. "A stranger opened the door and said, 'Hi, who are you?'"
The stranger ran, and though the resident followed her in a car, she got away.
Petaluma's evidence room is full of stolen items found last week hidden at a clandestine campsite at the Adobe Creek Golf Course, including power tools, sports equipment and other random items such as two coin collection books, Lyons said.
In Rohnert Park, officers handled 13 residential break-ins between June 1 and July 25 this year, compared to six during the same time period in 2012, Lt. Jeff Taylor said.
In one case, tracking software on a woman's iPad reportedly taken from her home July 22 helped the woman alert police to a Kenwood address, Taylor said. Sonoma County sheriff's deputies went to the address and found the iPad. They are pursuing a suspect, he said.
At the end of 2013, the Rohnert Park Public Safety Department will take a deeper look into why a June spike in burglaries occurred.
"These are numbers that we are monitoring," Taylor said. "When we do our year-end report, one of the questions we'll ask is, why?"
Many factors cause the ebb and flow of reported crime, he said. "We've had several recent daytime burglaries where the suspects went through open windows."
Crime analysts are looking into the effect shifting some state prisoners to county jails to lessen prison overcrowding has had on local crime rates. The realignment of state prisoners has prompted local jurisdictions to emphasize early-release programs to make room for the additional inmates.
The program is approaching the two-year mark this fall.
Lyons and others said it will take detailed analysis of who is committing the crimes in order to understand how — and if — realignment has contributed to the recent uptick.
Officers often start by investigating who is on probation in the area for a prior property crime conviction, Santa Rosa Police Sgt. Mike Lazzarini said.