On Monday, May 28, 2018 at 11:40:30 AM UTC-4, condo owner wrote:
A wing of garages are detached from the condos.

When the condos were built in the early 1970s, the farthest garage from my condo was assigned to me and the nearest garage was assigned to my neighbor.

When I complained about that, the condo board re-assigned the garages so my garage is now closest to my condo. The condo board also had to switch the electrical service (to match the new arrangement).

Could the "sparking" white wire still be controlled by my neighbor's circuit panel?

Sounds like you're on the right track. Perhaps something got screwed up
when they switched the electrical service. They could have just moved
the hot connection from your unit to the other guy, but not the neutral.
That would produce the symptom. But they must have moved the hot, I'm
assuming you checked that it's dead with your service disconnect open?