"The former captain of that boat was killed during a morning run less than a month ago"

Assassinated by either Russian dissidents or Ukrainian agents. He posted his runs on the fitness app Strava and his Strava feed was being followed by the head of Ukrainian intelligence!

https://www.strava.com/athletes/14384072

I typed his name Stanislav Rzhitsky into Google Translate and the copied the cyrillic text into the strava search. ( Станислав Ржицкий )

Then in the coments for a bike ride on July 9th people commented on it:

Jonathan Bird "Are you dead?"

and Gerrit Knol-

"ey mate. Hope you're doing marvelously well! Why didn't you upload your last run? Oh wait... 0:)"

Stanislav Rzhitsky has posted no Strava since July 9 where before he was a regularly uploading data.