Final answer:
Lord Capulet knows Juliet is dead when he finds her lifeless body in her tomb in Romeo and Juliet.
Step-by-step explanation:
In the play Romeo and Juliet by William Shakespeare, Lord Capulet knows that Juliet is dead because he finds her lifeless body in her tomb. He has heard about Juliet's death from Friar Laurence, but seeing her lifeless body confirms it for him. The play concludes with Lord Capulet and Lady Montague mourning the tragic deaths of their children.
The nurse and Lady Capulet tell him that she is dead and he, too, becomes very upset. He says her death is unfair for someone so young and beautiful, like a strange, unseasonable frost killing the most beautiful flower in a field.
Capulet is most to blame for the deaths of Romeo and Juliet because he over pressured Juliet to marry Paris. Juliet was married to Romeo at this point in the story. When she refused to marry Paris her father Capulet became extremely angry and threatened to disown her if she did not go through with the wedding.
Lord Capulet personifies death when he says, "Death is my Son-in-law, Death is my heir;My daughter he hath wedded." He personifies death by saying that death has married her daughter on her wedding day, not Paris, who was supposed to be his son-in-law.