Well played! You killed the walker with your extra action.

Not actually so risky if you make the comment with IF statements:
Action 1: search
Action 2: If search successful, search again. If zombie found, attack zombie for remainder of actions. Please make rolls for me in either case.

That lets me know you will not be checking back to make the required rolls and I will do them for you. Otherwise, you can do the rolls yourself; you just won't find out WHAT items you found until I respond, but you can plan the next action knowing from the roll(s) what the result is.