When I arrived at work on Saturday, I was pleased to learn that two more people had been arrested in the murders of a policeman and a security man at the W. Bell store.

Staff writers Loretta Tofani and Joseph E. Bouchard had prepared an update on a case in which police had begun with virtually no clues, yet within 24 hours had developed enough solid leads to begin making arrests. Once again, lawmen had demonstrated how effective they can be when enough of them are assigned to a case.

A shorter crime story covered by Tofani also caught my eye. It said that a year ago, the Internal Revenue Service began a quiet investigation of four of its own agents -- three of them inspectors, no less.

Over the weekend, police charged that one inspector had purchased four pounds of marijuana from an undercover policeman. Three of the four suspects were charged with "possession and distribution" of marijuana.

As marijuana busts go, this one is small potatoes. If tobacco were made illegal, my wife would be constantly subject to arrest for possession, but you could never pin a "distribution" rap on her because she can smoke up four pounds of the stuff in a single afternoon, all by herself. There wouldn't be anything left to distribute except in the form of ashes that had dropped into whatever she was fixing for dinner.

Four pounds of marijuana do not, therefore, translate into very many cigarettes or a major news story. However, several aspects of this incident did hold my interest. For example:

What triggered IRS's suspicion a year ago? Had the suspects suddenly begun spending too much money?

Does IRS keep closer watch on its own inspectors than on you and me?

If IRS agents are smart enough to know all the tricks used by the public, and if inspectors know all the tricks used by agents, why aren't inspectors smart enough to realize that somebody on the next higher level is wise to all the tricks used by inspectors? Why does everybody who breaks the law think he's the only one who is too smart to be caught?

Who watches the people who watch the people who watch the watchers?

Do IRS agents who traffick in marijuana pay taxes on their profits? If these fellows didn't, is that what led to their downfall? Aren't they aware that Congress demands a share of all earnings, "from whatever source derived"? t

It may be that one reason these questions held so much interest for me is that I have recently been wrestling with my income tax return.

Several years ago, four friends and I sold a farm we owned. Two of the four are lawyers, and one lawyer is also an accountant and a former employee of IRS, but they said the partnership needs a certified public accountant, so we retain one. Each year, the CPA fills out a Schedule K for us, files it with IRS, and gives each of us a copy of what he has reported. You might say it's the partnership version of a W-2 form.

On line 8 of this year's Schedule K, our CPA told IRS that my share of the partnership's long term capital gain in 1980 was $69. On the form, alongside this entry, is the printed enjoinder: "1040 filers enter amount in col. b on Form 4797, line 1."

So I entered the $69 from line 8, Schedule K, on line 1, form 4797, the instructions for which ordered me to transfer the $69 from form 4797 to Line 8 of Schedule K -- which is where they came from in the first place! I phoned our CPA and in a small voice squealed, "Help!" The CPA studied the matter for a while and then said with a sigh, "It certainly is confusing, isn't it? If I were you, I'd just list it with my other capital gains and losses, and if that's not where they want it, they can tell you that you put it in the wrong place. But at least they won't be able to charge you with not paying tax on it."

I will, of course, do as he instructed and render unto Congress, whatever part of that $69 it wants. However, I think most of us would be grateful if Congress were some day to translate its tax code into plain English.

One such person would surely be my colleague John Murphy Scott. Jack was not in a good mood when he came to work on Saturday.

His first words to me were, "I have decided that the Constitution needs one more Amendment -- one that says: 'All elections for Congress shall be held on the first Tuesday after April 15.' If people voted while form 1040 was fresh in their minds, I'll bet there'd be some wonderful changes made."