While looking around uboat.net the other day, I was curious about what they had on Kapitänleutnant Heinz Eck, commander of the IXD2 U-852. He was executed, along with two of his officers, November 30, 1945 for destroying the lifeboats of the Greek merchant steamer Peleus. He was the only u-boat commander convicted of killing survivors.
Uboat net includes an interesting article(taken from a book) on the incident in quite a lot of detail, including the trial- if that is what it can be called.
It is a four chapter article. The link below takes you to the first chapter. There are links to the other chapters at the end of each.
http://uboat.net/articles/index.html?article=18&page=2
Guilty or not, the trial was a travesty of justice. The defense had no time to prepare, the British Judge Advocate wouldn't allow them any time to prepare and he pretty much had the defendants guilty in his head and would do anything to make sure that was going to happen. The defense made some crucial mistakes when Eck took the stand to testify.
I found the use of "Operational Necessity" as a defense quite interesting. Basically, Eck felt the wreckage would put his sub at risk from strong ASW forces in Freetown and he wanted to eliminate the wreckage to make it difficult to pinpoint his position. Other nationalities have used "operational necessity" as justification to eliminate surviviors of a sunken ship. Some are detailed in the article.
I can't do justice to the article and the conclusions here. Read the article. It's a little long but very interesting.