 In his memoir "A Forger's Tale", written in prison, Greenhalgh claims as a 17 year old to have forged the drawing by obtaining an old piece of vellum from a reused 1587 land deed.Kemp said he found the claim hilarious and ridiculous.The work of art was studied on the PBS program "NOVA" in 2012 in a program titled "Mystery of a Masterpiece", from NOVA/National Geographic/PBS, which aired on January 25, 2012.