JACKSON, Miss. (AP) — The bomb-sniffing military dog that made national headlines when he was adopted by a fallen Marine's family has now died of cancer.A 2007 rocket explosion in Iraq killed Cprl. Dustin Lee and injured his canine companion, Lex. The dog stayed by Lee's side on the battlefield, and medics had to pull Lex away from the 20-year-old Marine from Quitman, Miss.The Marines later allowed Lee's parents to adopt Lex — the first time the corps had allowed such an adoption. Lex lived most of his final years in Quitman, a small town in east Mississippi.A Marines spokesman says Lex died March 25 in Starkville, where he had been undergoing treatment at the Mississippi State University veterinary school.The Mississippi House on Friday adopted a resolution honoring Lex.