Ex-NFL star Aaron Hernandez hangs himself in his prison cellBy JIMMY GOLEN, AP Sports WriterBOSTON (AP) — Hours before his former New England Patriots teammates were due to visit the White House to celebrate their Super Bowl victory, prison officials say, Aaron Hernandez tied one end of his bedsheet to a window and the other around his neck and hanged himself.In a maximum-security prison outside Boston, about an hour from the stadium where he played alongside stars such as Tom Brady and Rob Gronkowski, Hernandez jammed the door to his one-man cell lest guards try to stop him and put an early end to the life-without-parole sentence he received for a 2013 murder.He was 27.Gone was the college football national championship, his own trip to the Super Bowl in just his second NFL season, and the $40 million contract extension he received as a reward. Just days after Hernandez was acquitted in a separate murder case, his friends, family and his legal team were searching for an explanation."There were no conversations or correspondence from Aaron to his family or legal team that would have indicated anything like this was possible," said his attorney, Jose Baez. "Aaron was looking forward to an opportunity for a second chance to prove his innocence.