Hallowed Murder - Ellen Hart
Where Hallowed Murder is concerned, our protagonist is Jane Lawless who runs a restaurant - in this particular book, she's also acting as an alumnus adviser for her old sorority, one of whose members has apparently committed suicide. Jane isn't so sure and decides to investigate, discovering that some of the people around the sorority have issues with both religion and sexuality that make them prime suspects in Alison's death.

It's very much a book of its time, since it's set in the 1980's, and the whole sorority thing is a complete mystery to me anyway - I didn't guess the identity of the murderer, though, so I expect that if I get the chance to pick up the next book in the series (Vital Lies) then I probably will...