What does 2 Samuel 4:11 mean?

'So why should I let you off the hook when you kill an innocent man in his own house, on his own bed? Shouldn't I make you pay for spilling his blood and wipe you out from the earth?' 2 Samuel 4:11 - Modern Text Bible

(David sees their act as murder, not justice. He makes it clear that killing a defenseless man in his home is a crime that deserves punishment.)