I think I can look at this with cooler eyes.
Dear Agent, (good)
The corpse drew more stares than it did as Miss Georgia.
Observation: With hooks, ask if you can see it used for a movie poster or first line on the novel's back. The opening line shows power, but lacks the extra power you want for a hook. Consider combining the first and second sentence. Rewrite a new hook. Make the hook five to ten words.
Yet, (combined the sentences) Sheriff Lightfoot discovered (heavy word - links with alliteration though) more to the murder (given and wordy?) than a dead diva (good alliteration) sprawled on Marsh Island’s (contradiction with second paragraph) ninth green. He failed her in life, but he would serve justice in death (potential confusion in clarity).
JUSTICE SERVED is (linking verb) a 95,000-word mystery. It races (good verb) through a five-week period (good timetable) on St. Simons Island (good specifics) (Which island is it? This or Marsh Island?) like Robert B. Parker’s Sea Change (remember your italics) (dangling modifier - you said Sea Change raced through St. Simons Island).
I’m (hidden passive) a member of (wordy) the Georgia Association of Writers, as well as (and) a participant (shady word choice) in the Scribblers’ Retreat Writer’s Conference (Conference? If a one-time meeting, remove).
Thank you for your time. (good)
Observation: Needs more in the second and third paragraph.
Wolfe