James Jonson is a person not actually encountered in the game, but mentioned Timeline which was published by PC Format magazine.
From the content of the article, he can be identified as a deceased American member of the Temple of the Morning Star from the 19th century, whose family died in a fire.
1895. After unsuccessful attempts to kill the Dodger, the Power of Belial informs Florentine that the Gardeners may have returned to the Tower. American Temple member James Jonson is killed after locating an entrance to the Tower. His family perish in the fire. The Temple are attacked by the Dodger and the Ire as they try to move the Mirror.