How to make a death scene more sad?

You need to really dive into the emotion. The best way to make a death sad is to show exactly how much the suicidal guy really loved his friend. You have to reveal the remorse and regret he feels, even though it wasn't his fault; it was a disorder. There aren't any physical details (i.e. holding the photo) I can think to add, so I think it will rely on your ability to describe their emotions intensely.