Trouble with memory?

Many of us have come across people that seem familiar to us, but we fail to fully identify them. What do you say at such times?
Grammar: place (verb) somebody – recognise somebody by connecting him with past experience; fully identify
Examples:

1. I know that man’s face, but I can’t place him.
2. Your face seems to be familiar to me, but I’m sorry I can’t place you.
3. I knew him very well, but I couldn’t place him.
4. I think I’ve seen her before, but I can’t place her.

When a person tells something to recall some past experience, he is jogging your memory.
Grammar: jog (verb) one’s memory – say something that will help someone trying to remember a thought, event, experience etc.
Examples:

1. You don’t remember who was with us that day? Here’s a photograph to jog your memory.
2. Police are hoping to jog people’s memory by showing them pictures of a car used in the robbery.
3. Alice related a few incidents that helped jog my memory, and I could finally place the man I was talking to.