About a month ago, I recounted the experience of five black Americans who sought to visit Israel last August, only to be detained overnight at the Ben Gurion Airport and put on the next plane for home.

An official of the Israel Embassy here said at the time that the incident was being investigated but that the airport authorities may have believed the group had some connection with "the illegal presence in Israel of the sect known as the Black Hebrews."

It now appears that there is more to the story than either the frustrated travelers or the israeli officials were willing to acknowledge at first.

The incident was first brought to my attention by Myrtle Washington, a lawyer and former seminarian, who said she took advantage of an organized tour in order "to see some of the things I'd read about -- Beersheba, the Wailing Wall -- things that meant something to me spiritually."

Donald Fuller, who lives with her, said he had decided to accompany her on the trip because he had the time and a little money and thought it might be interesting.

Both said they knew nothing of the Black Hebrews, or the Hebrews Israelites, as they are also called.

But Fuller's ex-wife, who says he abandoned her in Portland, Ore., says Fuller had been involved with the sect for some time. She said the group had given them an expense-paid trip to its Chicago headquarters in January as well as a trip to San Francisco last fall.In addition, she told me, the Black Hebrews had also given Fuller a trip to Liberia earlier this year.

Fuller, when pressed on the question, at first said he "vaguely" remembered hearing about the Black Hebrews "back in the '60s" but had had no contact with its representatives until he started doing some research into the sect after his abortive trip in August.

He subsequently acknowledged the Chicago visit, but said he paid the expenses for himself and his wife out of his own pocket.

Fuller has sinced formed the Black American Human Rights Steering Committee, which has been picketing the Israeli Embassy and in general protesting the Israeli government's treatment of blacks, whether casual visitors or permanent settlers in Israel.

Fuller and Washington told me they learned of the August tour through the Rev. Willie Wilson, a Baptist minister here. At a press conference called by Fuller's group to announce plans for a demonstration during the recent visit here of Israel's Prime Minister Menachem Begin, Wilson said he had taken a similar tour himself.

"I recommended this particular tour rather than the usual tour because it gives a chance to see some things that you don't see on the regular tours." He said the special tours are arranged through the Hebrew Israelites.

A spokeman for the Israeli Embassy here says his government has "proof" that another member of the August party was affiliated with the Black Hebrews.

Clearly at least some of the members of that group were not as innocent of knowledge of the sect as they led me to believe. But that fact doesn't begin to answer all the questions.

For instance: Who are the Black Hebrews? Why, if their presence in Israel is illegal, have they been permitted to remain there for 10 or 11 years? Why is the Israeli government so distrubed over their presence? Is there truth to the charges that black American visitors to Israel are almost routinely detained?

I'll look at some of these questions in a subsequent column.