Who is Captain Matthews from Darkly Dreaming Dexter and what is their importance?

Captain Matthews is the head of the homicide division and Dexter's superior. He makes the decision to put Deborah on the Tamiami Trail killer case because he knows her father, and he is aware that she has connections in the prostitution community. Deborah sees this as a sign of trust, and she hopes to use it to gain a promotion. Later, when LaGuerta makes an arrest, Deborah goes to the Captain and tells him she does not believe LaGuerta has the right man. When the killer kills again, Deborah, who had previously appeared insubordinate, looks as though she is a gifted detective. Deborah hopes the Captain will give her a promotion, but instead he allows LaGuerta to continue to block Deborah's ambitions by keeping her out of the action.