Chester

Dr. Chester was a British citizen living in London in the mid-nineteenth century.

In 1868, Chester worked as a doctor in the City of London, where he bore witness to the murder of John Ashton, commonly known as the most hated man in London, who was crushed by a falling crate. Upon closer inspection, Dr. Chester determined that the crate had not necessarily been fatal, since Ashton also appeared to be poisoned, stabbed, and shot.

When questioned by the Assassins Jacob and Evie Frye, he urged them to consider all the possibilities, and only arrest the actual murderer, rather than bringing in all of the potential murderers.

Reference

 * Assassin's Creed: Syndicate - The Dreadful Crimes