Is it possile to break a person's neck if they are standing on the hood of their car hood?

i'm not really sure who to ask but it's like this my nephew was found 2 nights ago hanging from a tree with a rope and his neck was broke he had a brace on his knee and was driving his Durango or to some a SUV they are ruling suicide and people was there and did nothing! Is possible and he had a 50,000 life insurance payable to his girlfriend! Help me please someone we need answer's !!!!! Thanking you now in advance for any answer's.