Take a look at thisl link:

https://tinyurl.com/sqdtmpf

Interestingly, Lenkov says that CBS canceled the show. It was not some sort of mutual decision to end it as some have assumed (Lenkov wanted at least another year). He notes that both O'Loughlin and Caan have talked about leaving for years but that they (the production comapany and CBS) always managed to make deals to get them back. This year CBS made no effort to lure either/both of them back.