In the past, the private investigation profession was recognized as the field of male competence, but there are more and more women dedicating themselves to this sector. The war of the sexes will never end. In Sue Grafton's book “K is for Killer” gender conditions influence investigation methods. To support my thesis, I apply the methods of inquiry with quotes from the book that support my thesis. Before investigation methods can begin, the detective must acquire a case, which is no easy task. Private investigators rely on their own marketing and advertising. The most common cases that are presented to private investigators are unsolved and/or forgotten cases left by the justice system or by suspicious wives trying to catch their cheating husbands. The importance of gender is prevalent from the beginning of the book. The victim's mother, Janice Kepler, knocks on the door. "Is this Millhone Investigations?" Millhone replies "We're closed, could you still come back tomorrow and I'll set you up with an appointment after you check out my book?" “Are you his secretary?” “I tried not to sound annoyed since the mistake isn't uncommon, I'm him.” (4). The mistake is not uncommon because women are seen as outsiders in the male-dominated world of work and business. Gender stereotypes give rise to the idea that women shouldn't do certain things. The first female detective was published in 1864, before there were even any official female police officers in existence. Back then women had to be protected from the harsh realities of life, plus there were many jobs deemed unsuitable for women and their feminine qualities. The evolution of women and women's rights has come a long way, and even today investigators are thought to be men first and foremost. Janice apologized: “It never would have occurred to me that you would be a woman” (4). The first method of investigation is collection