Do the right thing, worry about consequences later. If society punishes you for doing good, then society needs to be changed. The best way to handle these problems is head on, so stay honest, be straightforward, and don't plot and plan a hundred ways to CYA.
Just do what's right.
If a gunman is shooting up a mall and either of my sons had a pistol and knew how to use it, I'd be proud of him for killing the shooter. I'd also expect him to be unflinchingly honest and cooperative with law enforcement afterwards.
If you find that lying is the solution to your problem, then how good of a solution can it be?