At the risk of sounding callous......
I really don't see what good is to be gained by "vigils". Same with making shrines out of accident black spots, it's just a place where something "nasty" happened, obviously to someone they knew, and holds no particular significance other than that's where your loved one/relative/ friend... breathed their last, re visiting those spots {sometimes annually} in some cases is of no benefit to anyone.
I drive along the highways and byways and see these bunches of flowers, scarves, football jerseys and/or photographs of the deceased usually pinned to trees and I just ask myself "Why!!!"
Surely making an annual donation to a charity in the deceased persons name will be of more benefit, to everyone.