The anime has its own original stories as well as drawing from the manga. I stopped watching the anime when it was in the 600's. At a point in time I had all 600 episodes on my hard drive. I suggest you read the manga if you want murders that more frequently relate to the plot of the series.
You watched from ep 1? Wow!
It was aired in the US for a number of years so I watched quite a bit when I was younger.