Atari is a famous video game company that has had numerous ups and downs in its history. In 2008, Atari was acquired by Infogrames, which re-branded themselves to match with the more famous name.
Infogrames acquired GT Interactive, publisher of the Blood and Blood II: The Chosen, in December 1999, one of the most expensive acquisitions in the company's history. This makes Infogrames the current rights holder to the Blood franchise, so if you want to write anyone about making a "Blood III" or releasing the Blood source code, this would be them.
A deal made in 2010 between Good Old Games and Atari allowed for the sale some of their older game titles and franchises on the service, something that made the Blood games legally available for purchase for the first time as a digital download. The games have since also appeared on Steam and can now be purchased directly from Atari's website.