The Pharm
The Pharm was a bio-research company on headed by Dr. Aaron Copley and located near Cardiff, which conducted experimentation on imprisoned aliens.
The Pharm's privileged access to the British government allowed them to conceal their activities even from UNIT (presumably) and Torchwood 3. To conceal their unethical activities, notably an experimental (and ultimately fatal) treatment using the eggs of Mayflies, Copley hired a killer to murder the Human volunteer test subjects. As well, the Pharm had developed a new kind of defoliant from Weevils.
Torchwood 3 having learned of the facility, Jack Harkness had Toshiko Sato set the computers to release inert gases throughout the facility in order to kill the aliens, whose lives the Pharm had essentially already taken. Jack shot Copley to death after Copley took the life of Torchwood operative Owen Harper. (TW: Reset)