Think about how much investigations through government agencies have changed since 1930?

Considering we still regularly still do lie detector tests, dog searches, entrapments, confessions under duress or even torture, I would say we haven't changed as much as you think.

That was also an outrageous and silly charge and representative a failure of the legal system to live up to its ideals of process and fairness. It wasn't especially political though, because by and large there is consensus that being a gangster should be illegal and that Capone was probably a gangster.

Attempting to take a popular political figure out by blatant abuse of the legal abuse is a bit more concerning.

Popular political figures aren't above the law, they aren't special because they are popular. I don't believe that popularity should be in any way a consideration to put someone up for a trial after they break the law.

I'm reminded of a quote from Pirates of the Caribbean: "One good deed does not excuse a man for a lifetime of wickedness!" "But it seems enough to condemn him!"

What crime, or type of crime, would you consider it OK to prosecute a popular political figure for?

I assume murder. What else?

Bit of a tautology, isn't it? I thought a crime was anything that it was OK to prosecute someone for.

The issue here is that people went looking for a crime for almost a decade, singling out Trump in a deranged crusade. Bush levelled entire countries. Obama put the foundations of the global spying apparatus in place. Biden might be on the verge of igniting WWIII with the policies of escalation that the US is employing.

Then in that background, there is speculation that Trump is going to be arrested for something related to Stormy Daniels after the levels of effort put in to pinning something on him? The people who feel that is appropriate can't serious. Based on what we've seen of the Trump saga so far, this is probably abuse of process. If that level of effort was put into another politician, they'd be in jail too.