Being a CT

[Pirate Rose]

I have a quick question seeing that I am new to JB after an about 2-year break. If I am a CT and see 2 people run out of the marker and then run back but only get one of their names and kill him right away when he gets to the marker can I do that or because I only got 1 of the names do I have to let the other guy go.

Thank you