Maybe because he was so good at escaping from prison?
And because they did not want the publicity of a trial? Especially since there would be supporters from the genral public?

I think it was partly malice; he'd made such fools of them that they just wanted to rub him out. And I think it was to make a big, bold statement that they really got him, put an end to his spree. And I don't think they were too confident that they could put him in a prison that would hold him!
(Have not noticed any stupid questions, Liz!! )

As they said in the movie, Dillinger was "wanted dead or dead." Dead men tell no tales! Dillinger would not be able to speak up and set the record straight, nor would he be able to escape again. It was a quick easy final solution to the FBI's problem and it created a lot more drama than a messy capture would have done.

P.S. I haven't noticed any foolish questions, either, Liz! Keep em coming.

John Dillinger was never to be taken alive after the FBI entered the picture. He had made the bureau and most jails look very inept. Also there were many law enforcement people and local politititans that needed to be protected.

Liz - there is no such thing as a stupid question!!!!!

I think it was made clear pretty soon into the search for Dillinger that he was not to be taken alive. He had too much fun with the press previously when he was arrested and if arrested again, they would have had to try him before they could send him to the chair. With his popularity it would have been a circus the FBI couldn't afford because they were trying to prove themselves not have a talking witness to so many of their mishaps. ( Especially one with nothing to loose if he was going to the chair.) Some of the torturing of witnesses proves how desparate they were to get him. It was something they had to make happen to justify their jobs.
I also found interesting the speculation in the book about it being necessary to shoot him because whenever he had been overwhelmed with too superior gun power he gave up peacefully and they wanted to make sure he didn't do it again.

I agree with what's been said so far. I'd also speculate that it might have been a direct order from Hoover. I think Hoover was mad as blazes that JD had made a mockery of his agency, and it might have become a personal vendetta for him.

That's right! Thanks for the reminder.

Liz - I think the questions have been great - they've certainly spawned some thought-provoking discussion!!

Guess he was too popular. A hero to the little people. Gives a person power. Makes others jealous. I feel he was executed. So, what did they really accomplish?? They just looked foolish once more.

I agree with everyone's reasons for the FBI wanting Dillinger's head. They just couldn't afford to let him live. He was a lesson to all would be criminals, this is what happens when you go up against the G-men. Hoover needed to assert his authority all the while sparking fear into the hearts of lawbreakers that might want to mimic Dillinger or his cohorts. He was pretty much turned into one big advertisement for the bureau. But killing him also turned into a last effort to manipulate the public. Dillinger was far too dangerous to draw another breath. We had to end it like this. It was a message to everyone thinking of a life of crime.