Hi, I just wanted to add my two cents/personal experience. I know this is an old thread.
I'm applying for the Fall 2015 cycle, and I've already gotten into a good Criminology Ph.D. program, and I expect to get into even more. I'm coming straight from undergrad with a B.S. in Computer Science, a couple psychology courses, a couple political science courses, a lot of chemistry and chemical engineering courses (I changed majors halfway through college, and I'm graduating on time) and an Applied Math minor. I have significant research experience in Materials Science/Chemical Engineering (and some Computer Science), some professional programming experience, and a government consulting internship. I'm hoping to do a policy internship this summer. I also applied with a 3.45 GPA...disclaimer, I'm from an Ivy League and have great GRE scores, but I think that just speaks to my credibility, and not my "qualifications" for a Ph.D. program. I have absolutely no criminology or sociology background whatsoever, just an interest and a lot of ideas in myriad areas across the field (not just in computer stuff - in fact, I de-emphasized that significantly in my applications).
What does all this mean to me? It means that you don't need to come from the "right" background, and it means that like many fields, criminology is an evolving and interdisciplinary one, especially in the 21st century. Your background seems more relevant than mine, and although everyone is different, I don't think you need a Master's to go for a good, funded Ph.D. program. Perhaps I come from such a non-traditional, though arguably useful, background, that people saw value in me. I chose this path with graduate school in mind, so my recommendation would be to figure out your education and career path in undergrad and make sure what you're studying will lead you down that path. Then, if you want to go into criminology, you'll already be sure that you're pursuing your goals your way. I'll report back to this thread later in the semester about my final prospects. But I think if you pursue your interests in undergrad and know what you want (I've known for a couple years that I wanted to go this route, but I didn't really do much about it except go to a couple seminars in a couple of my areas of interest), then you can do whatever you want. I suppose it is a gamble for a Ph.D. program to pick me, but I honestly never expected to get rejected, because in my mind, what I'm doing in undergrad all fits together, even if it doesn't fit into some curriculum dictating how the study of crime should be approached. That's all.