BEagle, this is one reason one gets upset,
Read page 5, this young lads ( a trainee ) screwdriver was found to have caused the pilots death, Though DNA testing found the pilot had come into contact with it, or it had been borrowed without his knowledge, it could have gone the other way and regardless of that this poor lad has to live with this for the rest of his life, even though it appears it may have been the pilot or someone else borrowing his screwdriver with out asking..
http://www.aaib.gov.uk/cms_resources...pdf_024587.pdf