Write a sequel to two existing novels - repost

I'm an author of two psychological, police procedural mysteries, which can be read separately or as a continuing novel. If you're a new writer who would like to inaugurate or jump-start a career by gaining a co-credit with this award-winning journalist, please reply to this ad. I'm interested in creating a mystery that has as a primary character a black man who was executed for a murder committed by his white lover and to which, because of his love for her, confessed. This murder takes place during the early 1940s in California, a state in which "mixed marriages" were forbidden by law. She later becomes a physician and freelances into selling babies taken from pregnant teen mothers. The story, and a subsequent murder of a new mom, continues to the doctor's death in 2012. The protagonist is a female detective, first introduced in "Alzheimer's: Dutiful Daughter," and who continues her search for truth in "Dedicated Doctor or Baby Broker?" Both of these eBooks will be provided to the selected author. I envision a "supernatural" story arising from the California execution of Abraham. When you reply to this notice, and in addition to sending samples of your talents, please enclose a page of ideas as to how you think the story would progress after his execution (or perhaps he did not die because of a reprieve or a reduction of his sentence). The story should include a "McGuffin" (a plot element that catches the viewers' attention or drives the plot; "the McGuffin was a key element of Alfred Hitchcock's films), that will tie the three books and its characters together. The book should contain quite a bit of dialogue, and should be written cinematically. It is our joint understanding that this book will be created as a "work for hire" with me retaining copyright. If the book meets my criteria, in addition to monies contracted for, you will receive a joint writing credit. Depending on the book's quality, I may be receptive to a future relationship in which both you and I would retain joint copyright and share the potential royalties. Currently, the two earlier books mentioned above, are available both as e-Books (Kindle, Nook, iTunes, Kobo) and as audiobooks from Amazon.