I had a situation a few months ago where a neighbors 10 year old daughter was killed in a car crash. Even worse his wife was the one driving. She lost control of the car and flew into a highway guard rail I barely know him and certainly didn’t know his daughter but of course went to be menachem avel.
Given the tragic circumstances I expected to find a big crowd on the Sunday morning when I showed but it was almost empty so I had to sit down directly across from. Being that at the time I had never sat Shiva myself I was at a lost for words when he looked at me expectantly. What was I supposed to say?
Now that I sat Shiva myself I’m more familiar with what to do. I would started off with “I’m so sorry that this is the circumstances that I’m here for…” and gauged his response and cues for what to say further. If I sensed he was no longer interested in me “I would have said “let me go take some mishnoyis…Hamokom Yinachem Eschem…” and made a slow exit