The initial fence Tran jumped did trip alarms in that area of the fence-line, but squirrels or even birds sometimes also set off the sensitive sensors, which could have lead to uncertainty about whether someone had jumped the fence or not.
Secret Service personnel removed the alarm sensors along an area of fence line when the agency raised its height in response to previous fence-jumping incidents as a way to make it harder to scale, the sources told the Examiner. Ironically, the very effort to prevent fence jumping appears to have permitted a particularly egregious intrusion.
One source said superiors in the Uniformed Division told Secret Service personnel to remove the sensors and piece them together for use elsewhere. They were never replaced.