what you could do is to post a message on the Swedish genealogy board asking the same question. There is an English section there and the people are really knowledgeable and helpful.
Make sure to provide all the details that you have in one post (including the name of his brother), which will help them trying to find him for you including these two URLs (death and marriage certificates). http://tinyurl.com/atmrr4shttp://tinyurl.com/ar3odw6
There forum is free of charge but you will have to register in order to create a post (don't worry, there are no spam emails sent out at all).http://aforum.genealogi.se/discus/
1. Get a user account, link at the bottom of the page
2. Then go to topics and choose "discussions in english", link at the bottom of the page.
I hope that helps