His third sacrifice

In the swamps, the body of a man was found, on the hand of which the seal is a Chinese symbol of forgiveness.
There are already five unsolved murders on the police account. The same handwriting, no connection between the victims.
Bella Richards knew the murdered person closely. Having moved to these places with her five -year -old son, she began a new life. Obviously, she does not find a place for herself from grief, but does not want to tell the police everything she knows.
Detective Talbot Dyson wants to entrust the case to his best employee. This is the inspector Matt Brindle, but he is out of the game. During the last raid on the criminal, he was seriously wounded, and his sergeant died. Nevertheless, he has to become part of the investigation and decide if he wants to return to his former life.
What actually connects the victims and who will be the following?