Persistent burglars are undeterred by recent improvements in home security systems because householders often fail to lock their homes properly or set alarms, researchers have found.
Most intruders interviewed for a new study were not troubled by alarms and dogs. They simply chose homes that offered easy access and escape routes and appeared "profitable'' targets.
Disturbingly, in the light of recent concern about householders being attacked by intruders, a fifth of the burglars preferred houses where they knew the residents were at home, asleep, as there would be more valuables such as wallets and handbags.
Almost half of the 50 persistent burglars interviewed for the study by researchers from Portsmouth University believed home security had improved over the past 10 years, but all 50 "felt security features were rarely enough to deter them''.
Only 14 said the most common reason for abandoning a break-in was "insurmountable security'', whereas being disturbed had led 22 to stop a burglary. Only 22 of the 50 said they would be put off by dogs, while alarms deterred only 17.
About two thirds of the intruders followed a similar "search pattern'' once inside the house, heading for the main bedroom, as the most likely location for hidden valuables, then moving to other bedrooms and living rooms which experience has taught them are also likely to contain items worth stealing.
The research, involving interviews with burglars in prison, suggests that one tactic that might disrupt them is to put valuables in unexpected places. In particular, most of the burglars considered children's rooms to be "rarely lucrative''.
The average time for a burglar to be in a property was only 20 minutes, though this netted them, on average, goods worth pounds 800.
The number of burglaries has fallen in recent years in England and Wales. However, the study - by Claire Nee, the Director of the International Centre for Research in Forensic Psychology at Portsmouth, and Amy Meenaghan - suggests that "target-hardening'' security measures offer only limited deterrence to "expert'' burglars.
The 50 men, aged between 21 and 60, had all committed at least 20 burglaries in the past three years and most of them had carried out more than 100.
The average age for the first burglary was 13 and a number had convictions for other offences, including armed robbery. Two thirds preferred to work alone.
Almost all the burglars decided "away from the scene'' that they would commit a burglary - with 39 of the 50 driven by a need for money - then searched for a suitable target, judging "profitability'' by the car outside or signs that there may be small, valuable items to steal. The "degree of cover'', such as fences or trees, was an influential factor.
The research, to be published in the British Journal of Criminology, does not support the common assertion that drug addiction drives burglaries.
It notes, that while two thirds had problems with heroin or crack cocaine during periods of burgling, only two of the 50 spent all their illicit proceeds on drugs, suggesting drugs were "an aspect of lifestyle rather than a driving force behind their criminal activity''.