Dark Room by Alison Tyler

Dani, a successful photographer, can't bring herself to face the death of her lover, Kate. An ambitious journalist, Kate was found mysteriously murdered, leaving her lover with not only fond memories of a too-brief relationship but dozens of unanswered questions about what might have led her to so tragic an end. Determined to keep the memory of her lover alive, Dani goes online under Kate's screen alias; and begins to uncover the truth behind the crime that has torn her world apart.