The first recorded use of the phrase 'pay it forward' was introduced into English in Lily Hardy Hammond's 1916 book "In the Garden of Delight": "You don't pay love back; you pay it forward."
While talking about other serial killers with long cooling-off periods, Reid mentions the Keystone Killer, from Unfinished Business (2006)
On Clarence Tipton's Colorado Department of Employment Service form, dated 07/23/88, his phone number is listed with area code 720 & his address as Bronson Springs. The area code 720 was not used until 1995. It is only used for the Denver metro area which includes all the surrounding suburbs.