[this is an extract from a wiki page about the Jigsaw (killer) from THE SAW movie]
The pig mask is a thematic prop worn by Jigsaw and his accomplices throughout the Saw film series to conceal their identities while abducting their “test subjects”. As the series continues, the purpose of the pig mask is explored in detail; it is explained to be a tribute to the “Year of the Pig”, the year in which Jigsaw started his work. [from me: 1995, 2007 are the years of pig]
The origin of the pig mask was shown in Saw IV, revealing the first known pig masks to have been latex strap-on masks used at a Year of the Pig Chinese New Year festival. Jigsaw had snatched them and donned one, while using the other one to hold his chloroform-soaked rag. The second mask was then used to knock out his first test subject, Cecil, by placing the mask over his head with the chloroform rag still inside.
When working on the original Saw film, writer Leigh Whannell and director James Wan wanted their antagonist to have some sort of mask. After some discussion, the idea of Jigsaw wearing a rotting pig’s head was chosen to symbolize his pessimistic view of the world and the disease that he was “rotting” from.
Nevertheless, the mask given to them from production (a rubber Halloween mask) was considered by them to be less than satisfactory. A number of things were added to make it look more gruesome, including long black hair and pus running from its eyes and nostrils. Whannell has still admitted to being disappointed with its final appearance compared to his intended one, but has admitted that the mask has since become one of the “staples” of the Saw franchise.
Along with Billy and perhaps Jigsaw himself, the mask has since become one of the more iconic symbols of the franchise. It has appeared on both the posters for the first film and the fourth. The mask has also been featured on many forms of merchandise. Officially-licensed pig mask replicas have been sold for Halloween. In addition, the mask has been featured on numerous Jigsaw action figures. NECA has released two Jigsaw figurines with the pig mask; the original was Jigsaw wearing the mask in his black cloak, and a Saw III variant of Jigsaw wearing it in his red cloak. In addition, the Be@rBrick line has released a “bear” version of Jigsaw wearing the pig mask. Medicom has also released a figurine of Jigsaw wearing his infamous pig mask in the “Real Action Hero” line.
On the commentary track of Saw IV, several discussions occur about Jigsaw’s decision to use references to pigs. In the series, the producers explained that Jigsaw was a spiritual person; however, it has never been revealed what religion he follows. In Saw IV, Jigsaw’s ex-wife Jill explains Jigsaw’s organized and planned lifestyle, stating that she had conceived their miscarried son Gideon, with Jigsaw planning for him to be born in the Year of the Pig. On the commentary track, the producers explain that in the Chinese Zodiac, the pig stands for fertility and rebirth. Jigsaw is seen several times throughout the series with figurines of clay soldiers and buddhas, further symbolizing his reference to various Asian cultures.