Complex sentence: Most victims reported having suffered burglaries or seen or heard an intruder on their property before the attacks, and police believed there was a pattern of reconnaissance being carried out on the houses of victims before the day of the crime.
Split into simpler sentences: Most victims reported having suffered burglaries or seen or heard an intruder on their property before the attacks. Police believed there was a pattern of the offender using reconnaissance on the houses of victims before the day of the crime.