Knit, purl, die / Anne Canadeo.

Enhanced descriptions from Syndetics:

Meet the Black Sheep knitters--five smart, funny women who love to knit, gossip, and solve crimes.

Gloria Sterling had it all--money, looks, and a new sexy young husband. So when she's found floating face down in her own swimming pool, shock waves ripple through tiny Plum Harbor. At the Black Sheep Knitting Shop, Maggie Messina and her circle are devastated to lose their dear friend--a woman as colorful as her fabulous yarn creations.

The police are quick to call it an accident, but sorting out Gloria's final hours leaves too many loose ends to satisfy her friends. The vivacious, fiftysomething cougar had her French manicured tips in more than a few pots, and the threads of some inside deals stashed in her chic knitting tote.

Who was the last person to see Gloria alive on that quiet summer night? Two empty wine glasses suggest she wasn't home alone knitting the entire evening... The Black Sheep need to know the truth and set out to unravel-- stitch by stitch--the weighty secrets that pulled poor Gloria under.