John L. Slocum was a Watcher active in the Dakota Territory, USA. During his life he observed several Immortals:
George Geddis - 1862 to 1863.
Roger Ludlow - 1863 to 1865.
Myra Clinton - 1866 to 1867 (her death)
Duncan MacLeod - 1867 to 1868.
Roberta Pembroke - 1868 to 1869 (her death)
In 1869 he was dismissed from the Watcher organization with predjudice, charged with having had physical relations and/or contributed to the deaths of Myra Clinton and Roberta Pembroke. It was also clear that he had falsified records and destroyed a Chronicle. He was allowed his freedom only with the threat that any breach of secrecy or attempt to exact revenge would result in a tribunal for treason, the punishment for which would be death.