This was for combined YM/YW.
Activity: I took this activity from this site - except that I changed all the suspects to names of the Young Men and Young Women leaders and the Bishopric members in our ward. I cannot believe I didn't save the document I created. I had the kids get into groups of 4 or 5 and go around the building asking for the clues. Of course, kids don't listen, so some groups ended up being more like 10 kids. It still worked just fine with bigger groups. The only rule I gave them was to please not run and shout in the church. Kids also don't listen to this rule ;)
What I'd do differently: We had a winner by 7:45, leaving 45 more minutes for kids to run amuck before their parents came. I don't know if there's a way to lengthen the game but it would be worth it in the future. Also, if I were doing this as an adult activity, I would do the "Clue and Fondue" version - meaning that the refreshments afterwards is fondue. We wanted to have a chocolate fountain to dip fruit in, but knowing teenage boys, we knew they'd stick their fingers in the fountain.