Hide Away by Jason Pinter

After her husband's violent death, Rachel Marin moves with her two children to Illinois from Connecticut. Since his passing, Rachel has become strong physically, in addition to not being afraid to take justice into her own hands. When the former mayor, Constance Wright, is found dead in what appears to be suicide, Rachel contacts the police to let them know that she believes Constance was murdered. Rachel then insinuates herself into helping investigate the crime when she believes the lead detectives, John Serrano and Leslie Tally, are getting off track. However, Rachel's involvement might put her family in harm's way yet again... A good read-alike for Thomas Perry's Jane Whitefield series.