Buchanan by Julie Garwood (I've read book 1, and books 7-12)
#4 Murder List
#5 Slow Burn
#6 Shadow Dance
I hate starting series in the middle, but somehow my OCD in book reading didn't really kick in with this series. While the books are interconnect each book can pretty much stand on its own. You get enough background when needed.
I think one of the things I enjoyed the most about these books was the outdated tech talk. The best were the discussions of cell phones having cameras in them and how unique that was at the time. In each case, it was thankful that one of the characters have one of these phones in order to take a picture of something important to the investigation.
The first book in the series was written 2000 and in the last 15 years so much has changed that these books seem so wildly outdated. Still they have great characters and I like the slight suspense.