Informal expression meaning covered or stained with blood; synonymous with 'bloodstained' or 'blood-soaked'.
事故現場で彼は服が血だらけになって座っていた。
At the accident scene he was sitting with his clothes covered in blood.
演出のため、俳優の衣装が血だらけになる特殊メイクをした。
For the production, special makeup was used to make the actor's costume appear blood-soaked.
小説のクライマックスは血だらけの描写が続き、緊張感を高めている。
The climax of the novel contains continued blood-soaked descriptions, heightening the tension.