Some statistics here suggest it is alot. http://www.associatedcontent.com/article/376041/murder_rates_and_violent_crimes_in.html
Captured - 2007 Ivy League Murders was released on: USA: 1 October 2007
The Cinema Snob - 2007 The Helter Skelter Murders 4-4 was released on: USA: 26 January 2012
Case Crackers - 2005 The Hog Trail Murders was released on: USA: 27 July 2007
My Secret Record - 2007 was released on: USA: 19 April 2007 (Nashville Film Festival)
the usa has more murders per year than every other country combined with a total of over 45k murders each year
Ghost Hunters - 2004 Manson Murders 3-12 was released on: USA: 18 July 2007
Lockdown - 2007 Total Control 1-6 was released on: USA: 2007
The Cosby Mysteries - 1994 The Lottery Winner Murders 1-1 was released on: USA: 21 September 1994 Hungary: 11 July 2007
Inside - 2007 Total Control was released on: USA: 13 October 2010
The Ever After Murders - 2014 was released on: USA: 2014
History's Mysteries Infamous Murders - 2001 Gangland Murders was released on: USA: 29 October 2004
History's Mysteries Infamous Murders - 2001 Red Light Murders was released on: USA: 2001