At any rate, “Have you seen....” posters might work. You know the posters. They are about 8X10 inches because they are usually printed on a home office printer. They are commonly used to look for pets. Right? A picture with a brief description.
Even if the person is out of the area, she/he had to do an in person research, no different than the the 911 bombers. The 911 guys staked out the New York buildings with cameras. However, if the Capital Hill Bomber, while doing research very well may have been seen. If that person was in an ally rarely visited except by residents it would be alarming and in that moment possibly a bit of a bonding with the moment enough to strike a memory.
Door to door questions by uniform officers and/or FBI would bring concern by the neighborhood and people will put their memories to work.
Good luck.
