On Oct. 7, Gov. Marvin Mandel of Maryland will be sentenced by a federal judge for mail fraud and racketeering. Mandel could be sentenced to more than a century in the penitentiary and hit with a $42,000 fine. Actually, if the judge were to suspend his sentence it wouldn't matter. The governor is ruined. By most accounts he is pancake flat broke and, at 57 years of age, he's getting past where you can start over.

The Mandel case, however, should be a warning, not to crooked politicians, but to anybody, that if the feds want you they'll nail you. It doesn't matter how big a bigshot you think you are, they'll get you. That is the only lesson a sensible person can draw from this most disturbing prosecution. Unhappily, though, the knee-jerk moralism of the media is so mindlessly reflexive that, if a word of protest has been written about this case, these eyes haven't read it.

The key to what stinks about the Mandel conviction is the mail fraud counts alleged against him. The mail fraud the governor is guilty of is sending, via the U.S. Postal Service, transcripts of his press conferences in which he is supposed to have lied.

Are we really to punish mendacious politicians by putting them in jail? Heretofore, kicking them out of office when their next November rolled around was deemed an adequate penalty for prevaricating to the public. Every politician in the country - excepting Jimmy Peanuts who has promised he will never do that to us - should take alarm.

Naturally the pols can't say anything. How would it look if they protested putting someone in the big house for telling untruths to wonderful us, the immaculate American electorate who commit no crimes and speak no lies in our business and professional lives. Moreover, Mandel compounded his felony by lying to reporters, those vigilant virgins of virtue, to mimic Spiro Agnew, that one famous student of journalism who, incidentally, was felled by the same federal prosecutor who bagged Mandel.

And where did the governor send these transcripts? He sent them a few miles away to the state archives of the University of Maryland library.

The federal mail fraud statute wasn't drawn to punish their self-serving and doubtless dishonest remarks in the warehouse for future Ph.D. candidates to yawn over. That law was passed for the purpose its name suggests, to prevent somebody like a Florida land swindler from using the mails to sell swamp lots to Minneapolis factory workers as retirement property.

Lawyers may congratulate Barnet Tom D. Skolnik, the assistant, U.S. attorney, who is chiefly responsible for this dangerous prosecution, for such a clever perversion of the law's intent.

The rest of us should mark, however, that what's been done is to twist the law into something it isn't in order to get somebody. The same can be said of the other count of racketeering of which Mandel was convicted. This law was enacted to protect society against Mafia-type organizations, not the State House rascality that Mandel and five associates were accused of.

The gist of the substance of the charges against the governor is that be used his influence to manipulate horse racing dates so his pals could secretly get ahold of a race track and make pots off of it. In exchange Mandel got loans, vacations and got cut in on some of the sirloin in a few business deals.

This is not Mafia-type stuff. Which is not to say Mandel may have not have done these things, but whether he did or he didn't, all the acts alleged were committed in the state of Maryland. No interstate or federal angle exists, ergo no reason for the feds. Maryland has courts, it has its own prosecutors and judges and laws; if the people of that state decide they're being ripped off by their officials, they can stir their stumps and bring 'em to trial. After all, Mandel was only governor, not dictator of Maryland; he could have been indicted at the state level.

We are told there is no such thing as a federal police force, but in this matter District Attorney Skolnik not only invaded turf from which he is constitutionally barred but he perverted the federal statues to do it. Skolnik should be given a testimonial scroll for his good work on the Agnew case, which did involve sure federal violations, and then be sent to private practice, where he can't do as much good nor as much harm. As for Gov. Mandel, Mediocre Marv. as some of his admirers used to call him, should have his convictions reversed on appeal.