"Only if it turns out that reality is actually nothing more than a holographic illusion created by the interplay of subatomic particles on a vast two-dimensional membrane."
This article covers a subject that has been deemed non-canon by either the author or the Back to the Future licensees, and thus should not be taken as a part of the "real" Back to the Future universe.
Mungo P. Tannen was a warden of a prison in Sydney, Australia during 1790.
At some point during the year, two bank robber (Frankie and Sidney) from 1992, crashed into the prison after their arrival to the time period. As a result, Mungo arrested them and put them to work smashing rocks.
After catching Einstein returning to the DeLorean time machine, the two bank robbers ran from Mungo, prompting him to pursue them. He was unsuccessful as a kangaroo that Einstein befriended bounced a hammer onto Mungo, while Einstein got the Delorean running.