Detective Freddie Costa
Freddie Costa is a detective for the Chicago Police Department, he was close with Ennis Roth's father Nate, who taught him everything he knew about being a police officer. Freddie is also on the payroll of the Lassiter shapeshifter family, acting as a liason, delivering messages to other families as well as making sure any monster activity/deaths attributed to monsters is covered up.
After the death of Tamara, Freddie attempts to question Ennis about what happened, not believing that it was a monster that killed Tamara. Not long after, Sam and Dean arrive posing as FBI agents and kick Freddie out of the interrogation room.
The next day, Freddie reports to Margo Lassiter about the concerns the other families have after the death of Sal Lassiter. Margo tells Freddie to tell the others that she runs the family. When David Lassiter arrives to the Lassiter residence, Freddie tells him to try and talk some sense into Margo, as he cannot before he leaves.