Outlander season 6 episode 5: Who is the whistling prisoner at the end?

gamesradar.com:

Outlander’s latest episode ended with a mysterious figure who could be heard whistling behind the bars of Wilmington prison. While we’ve yet to see his face, theories have begun piling in about who the character could be.

Episode 5 shifted the drama from Fraser’s Ridge to Wilmington as Claire Fraser (Caitriona Balfe) and Jamie Fraser (Sam Heughan) went to visit Aunt Jocasta (Maria Doyle Kennedy). However, the trip was not without its drama as the newly introduced Flora MacDonald (Shauna MacDonald) found her rooms being ransacked by a mysterious thief.

Her emerald necklace was returned with one jewel missing, which can be seen in the hand of a mysterious prisoner at the end of the episode. The final few moments show him whistling a tune, which Claire hears through the wind as she heads back home.

Their identity is yet to be revealed with only their long black hair seen in the brief shot. Yet, the main contender appears to be Wendigo Donner (Brennan Martin). The character was briefly introduced in the show’s season 5 finale as one of the men involved in Claire’s abduction. 

Wendigo is a fellow time traveler, who made himself known to Claire by asking if she’d ever heard of Ringo Starr. The character is one of the Montauk Five, who were a group of five activists from 1968 who traveled through the stones just like Claire did. 

We were unfortunately only treated to a brief scene with him last season before he disappeared as Jamie located, and brutally killed, Claire’s other abductors.

Now it seems likely he’s back after the glimpse of his long hair as well as one particular clue that proved it was a time traveler whistling the tune. The song in question is Colonel Bogey March, which was composed in 1914, long after the events