Jigsaw appears in flashbacks in the film. One flashback set prior to the events of the first film showed that it was Amanda Young who sent Adams to Jill Kramer's clinic to steal drugs for her.
This resulted in Jill's miscarriage, and thus Young was revealed to be an indirect cause of John Kramer's transformation into Jigsaw.
Further flashbacks set prior to the events of the first film reveal that Jigsaw targeted William Easton for one of his games because William, without any sensitivity, had denied him health coverage after he developed cancer.
In the present time of Saw VI, Kramer shows himself on video twice to Easton instead of the Billy Puppet (the method Kramer usually used to speak to his subjects), so Easton could look in the eyes of someone he let die.
In another flashback, this time set between the events of the first and second film, Jigsaw explains to his ex-wife that his "rehabilitation" works, showing Amanda Young as supposed evidence of this.
A flashback set just before the events of the third and fourth films explores the group dynamic between Jigsaw, Amanda Young and Hoffman. Jigsaw criticises Hoffman for not seeing the test subjects as human beings and also critiques his approach to setting up Timothy Young's trap.
It was also shown that Jigsaw seemed to have had a closer emotional attachment to Amanda Young than Hoffman. Shortly afterward, Jigsaw gave his ex-wife the key which she later used to open the box he gave her in his will in Saw V).
In the present time of Saw VI, it is revealed that the box contained six envelopes (marked 1 through 6), a thicker envelope, and an updated version of the "Reverse Bear Trap".
She gave Hoffman envelopes 1 through 5, but hid everything else from him and later delivered the thick envelope to an unknown person.
Envelope 6 was meant only for Tuck-Kramer, instructing her to trap Hoffman and put the "Reverse Bear Trap" on him so he could be "tested".
This fulfilled the promise made, via the audio tape discovered in the stomach of Jigsaw's corpse, that Hoffman would not go untested.
Jigsaw reappears in Saw V, in flashbacks meeting with Hoffman, attacking and kidnapping Paul Leahy, then setting up and later watching his razor wire trap from Saw, as well as setting up the house of Saw II.
He is shown on his deathbed talking to Hoffman about setting up a test, which leads Hoffman to exit the room as Young enters with Dr. Denlon, which occurs near the beginning of Saw III. Jigsaw also appears in a video will to his ex-wife Jill Tuck-Kramer, leaving her a mysterious box.
His deceased body is shown several times during the start of the movie, which was also the end of Saw IV, an opening scene in which Peter Strahm receives his first cassette tape, and a flashback which occurs to Strahm later in the film.
Employed in a cancer hospital is ain't a easily digestible one no matter how long you work there...
But life teaches you to appreciate even the tiniest bit of happiness compared with the suffering that one has to go through..
Life Goes On ..
No Matter What !!!