Rep. L. Richardson Preyer - former federal judge, five-term member of Congress from North Carolina and present bigwig on the House assassinations committee - is an old friend. He is also, unfortunately, the very paragon of discretion and lawyerly restraint, so that my efforts over lunch the other day to extract a theory of the assassination cases from him in advance of the full hearings got me nowhere. But as I rode back to my office through Washington's steamy gloom, it occurred to me that the silence was the story.

Preyer had declined to dismiss out of hand the various theories I put forward, never mind how sinister or rococo they might be. There was a time when such a conversation simply could not have taken place between two such thoroughgoing political squares. I would not have given house room to the questions that were now on my mind. And he would not have taken them seriously enough to suggest that they would be answered as best they could be by the facts the committee was seeking to unearth. Fifteen years ago when John F. Kennedy was killed, and five years later when Robert Kennedy and Martin Luther King followed, I thought the killings themselves represented the outer edge of the unthinkable. Now here I sat trying to get a reading from my friend on what he thought might have been the role of the KGB, Cuban intelligence, anti-Castro groups, organized crime and - yes - the CIA and the FBI.

I don't think I am merely describing a personal turn of events. I think the country as a whole has experienced a certain cumulative fall from innocence over the past decade and a half that is going to make it much harder - if it is even possible at all - to resolve the ugly, gnawing questions about the assassinations.

The House committee, which is charged with investigating the King and JFK murders, held far more dignified and effective public hearings last week than anyone expected on the basis of its boisterous beginnings. And it seemed to me to deal a pretty conclusive blow to James Earl Ray's claim that he was not the killer of King. But I still don't feel confident that I know who or what James Earl Ray is, any more than I know those things about Lee Harvey Oswald. I'm not saying that I subscribe to any particular conspiracy theory. I'm saying that I don't think the House hearings will be able to answer myquestions or resolve my doubts, no matter how fair-minded and painstaking they may turn out to be.

Now the fact is, as any good lawyer will tell you, that coincidence is not nearly as significant is the untrained are inclined to think. "I could take the natural death of any relative of yours," a former Justice Department student of the King case told me, "and come up with a whole collection of coincidences that would suggest murder." The observation was made in response to my expression of discomfort over the extraordinary mortality rate of individuals who were scheduled to testify on the assassinations or who already had: Sam Giancana and John Rosselli, two slain mobsters; George de Mohrenschildt, a friend of Oswald's pronounced a suicide; and William C. Sullivan, the FBI man most importantly involved in both the Kennedy and King investigations, killed a hunting accident.

The columnist Mary McGrory, whose apartment was broken into twice in the past decade, once observed, in the perfect phrase, that until all the information about political plumbers and bag jobs came out, she had always assumed her robberies were the work of "honest burglars." Likewise I - and I expect many others - would at one time simply have accepted the murders of Giancana and Rosselli as what you might call innocent, benign gangland slayings. The good Lord knows that strictly in terms of mob warfare there was ample explanation for self-evidently a suicide - and the hunting accident demonstrably an accident.

I accept it all. But it still doesn't sit right, doesn't satisfy the doubts. And this is true despite my profound temperamental aversion to much of the conspiracy subculture that has sprung up around the assassinations. And for this, as distinct from the bloody acts we are talking about, I have no hesitation to blame the various guardians, so-called, of the national well-being. On the one-hand, i have a set of facts and explanations, perfectly logical and plausible in themselves, that argues for the culpability of Ray in the King killing, with or without the help of some others - but surely without any official collusion. On the other, I have something else: an apparently endless stream of revelations about the frenzy of spite the late J. Edgar Hoover and the FBI felt against King and the deranged, obscene campaign they waged to bring him down. Intellectually, you can persuade me of the irrelevance - the "coincidentalness' - of all this. But still it hovers as a profoundly uneasy feeling, always, over judgment.

The Kennedy case is more of the same. We know things now we didn't know before about the Warren Commission and its manupulation on certain crucial matters by the CIA and the FBI. We have all had an unwanted education in the fine art of disinformation, been treated to near-boasting accounts of how the intelligence agencies created false realities for our delectation. We follow threads from JFK to th slain gangsters (via Mrs. Exner) and then to the CIA and the hiring of the same gangsters to do in Castro, and there the thread snaps. We know that both the CIA and the FBI withheld relevant, maybe even crucial information from the Warren investigators. The best that can be said of this is that they were trying to protect their own vanity and reputations or protect the public form material they thought it could not be trusted to understand - or some combination of both. The worst that can be said fills the growing literature of conspiracy.

It is an irony of our perplexed, unhappy condition concerning the assassinations that we owe much of our unease to ealier efforts to "reassure" us. I can remember talking to Sen. Richard Russell 14 years ago about the Warren Commission, which he ahd more or less thought up and on which Lyndon Johnson compelled him to serve. Russell would pore conscientiously at night over the piles of printed material. He was investigating. And yet his every instinct pointed in one direction: to reassure the public - not merely that it had the facts, but above all that the crime was contained explained, less than it seemed, perhaps, but surely not more.

Now, all those years and revelations and disillusions later, this innocent instinct (I insist it was that with Russell and most of the others) may be seen as a cause of our doubt and distress. People like Richardson Preyer indulge only the modest hope of reassuring the public that it has all the facts that should be available to it - and they cannot even be certain of providing such limited reassurance as that.