Keira Knightley
Loretta McLaughlin

Carrie Coon
Jean Cole

Chris Cooper
Jack Maclaine

Alessandro Nivola
Detective Conley

Rory Cochrane
Detective Deline

David Dastmalchian
Albert DeSalvo

Peter Gerety
Eddie Corsetti

Robert John Burke
Eddie Holland

Morgan Spector
James McLaughlin

Michael Malvesti
Detective Donovan

Nancy E. Carroll
Mary McDermott

Therese Plaehn
Kelly

Stephen Thorne
Frank Cole

Greg Vrotsos
George Nassar

Ian Lyons
Gordon Nielson

Christian Mallen
Paul Dempsey

Pat Fitz
The Killer

Pamela Jayne Morgan
Anne Samans

Robert C. Kirk
Arthur

Charlie Thurston
Fritz

Kate Middleton
Phyllis

Ivan Martin
Stanley

Kate Avallone
Lifestyle Editor

Tamara Hickey
Ellie

Luke Kirby
F. Lee Bailey

Thomas Kee
Richard DeSalvo

Kyra Weeks
Emmie

John Lee Ames
Harrison

James Ciccone
Detective Linski

Bill Camp
Commissioner McNamara

Jimmy LeBlanc
Officer Dougan

Gary Galone
Belmont Detective

Josh Drennen
Sergeant Burke

Brian Faherty
Officer Sullivan

Michele Proude
Anna Slesers

Grace Aiello Antczak
Claire

Rosemary Howard
Helen Blake

Kris Sidberry
Sophie Clark

Kate Lynch
Beverly Samans

Erin Rose
Assault Victim

Caitlin Zerra Rose
Young Woman

Paula Plum
Mrs. Quinn

Danny Connelly
Building Super

Frank Ridley
Ida's Super

Bill Mootos
Dr. Grayson

Jennifer Lafleur
Nurse Patty

Danielle Perry
Nurse Deb McNulty

Moira Driscoll
Psych. Orderly

Victor Warren
Director

Bill Thorpe
Brawny Detective

Mike Bash
Inmate

Marissa Carpio
Production Assistant

James Wilcox
Police Examiner

Michael Tow
JC Kim

Jonathan Fielding
Herald Reporter

Owen Burke
Officer Shanley

Al Conti
Boston PD Detective (uncredited)