2 Chronicles 22:9

New King James Version

^9 (A)Then he searched for Ahaziah; and they caught him (he was hiding in Samaria), and brought him to Jehu. When they had killed him, they buried him, “because,” they said, “he is the son of ^(B)Jehoshaphat, who ^(C)sought the Lord with all his heart.”

So the house of Ahaziah had no one to assume power over the kingdom.