Many years ago I was walking down the street when several patrol cars quickly pulled up, police jumped out and sternly stated, "Stop. Can I see some ID?" (with hands on guns/tasers ready for a chase).
Naturally I stopped and showed ID. No problem.
Once the officers saw I was cooperative and not trying to be difficult, they lowered their defenses and became much more cordial.
I learned that I "matched the description" of someone who apparently had just moments before committed an armed robbery a few blocks away. Okay, so I get why I was stopped. Again, no problem. They took my information and let me go on my way.
A few days later, two officers knocked on my door and asked if I would "come down to the station to be part of a photo line-up." Note that I have no criminal record and there is most likely nothing "on file" that would have been sufficient for the police to use.
Due to my circumstances - just got off work, had a job that left me smelling of gas, tar, and asphalt and very, very greasy and grimy and I hadn't had a chance to clean up yet - I politely turned down their request. This wasn't a problem. The officers went on their way.
Much later I read somewhere that one should never pose for a photo line up because if the "witness" makes a mistake you could be in a whole lot of trouble quickly with little or no cause for it.
Is it ever a good idea to pose for a photo line up if you haven't been charged with anything?