FEW WILL BE surprised if it turns out that Ayatollah Khomeini or some branch of his apparatus in Iran was standing behind the man who murdered Ali Tabatabai, an Iranian exile and active political foe of the Khomini regime, in his Bethesda home yesterday. Retributive "justice," meted out cruelly and without regard to any accepted procedural standard, has been one of the distinguishing marks of the Iranian revolution. Hundreds of Iranians have been executed by the regime inside Iran, while outside Iran the ex-shah has a huge price on his head and just the other day an attempt was made on the life of a former Iranian prime minister now living in Paris. Mr. Tabatabai himself had warned that the regime's secret police were after him. The people of Washington may be shocked that he was assassinated in this very community, but the fact is that murder is, for the regime, a very common and typical affair.

Evidently -- with or without this particular killing -- the ayatollah and his comrades in the Iranian leadership have forgotten the long years of their own exile in which they enjoyed sanctuary abroad. Many in the regime, of course, have enjoyed hospitality, often including the opportunity for study, in the United States, the country whose hospitality to one of their political foes they seem now to have abused so grossly. If this is established, it cannot fail to cloud further both the attitude that Americans have toward the Iranian revolution and the specific prospects for future relations between the two governments. Meanwhile, the United States owes it to its tradition as a haven for political refugees to pursue with the utmost diligence the search for the killer of Mr. Tabatabai. The assassin should be brought to justice and his foreign links, if any, made clear.