First, per a league source, the other “area on way to field” is a bathroom.  The bathroom consists of one toilet and one sink and a door that locks from the inside.

Second, according to the same source, the person carried two bags of balls into the bathroom:  the 12 balls to be used by the Patriots and the 12 balls to be used by the Colts.

Third, from the same source, the evidence comes from a surveillance video that was discovered by the Patriots and given to the NFL early in the investigation.

Fourth, again from the same source, the video shows the employee in the bathroom for approximately 90 seconds.

Could the employee have fished 12 balls out of a fairly large bag, deflated each of them by two pounds, put them back into the bag, and exited the bathroom in roughly 90 seconds?