A lawsuit filed against an American educator who is one of the U.S. hostages in Iran resulted yesterday in what the businessman who filed the suit said were death threats against him. The businessman said he had filed the suit without knowing the educator was a hostage.

The suit filed by Orest Fedoronko in Warminster (Pa.) Small Claims Court last July 6 against William F. Keough and his Tehran American School seeks to collect $406.50 allegedly owed for a check writing machine.

Keough, of Alexandria, is one of 52 Americans held hostage since the takeover of the American Embassy in Tehran Nov. 4.

"I had absolutely no idea he was a hostage," Fedoronko said yesterday. "I was just pursuing a simple debt and now people are telling me I could get killed. would like [Keough's] family to know I would never have filed the suit if I'd realized what the situation was," Fedoronko said.

Since Keough's identification as a hostage was revealed in court papers filed by Keough's lawyer Tuesday, Fedoronko said "a guy called and told me to watch out when I turned a corner, and another guy called and said, 'you're dead.' It's very discouraging. I'm 69 years old and don't need the aggravation."

The dispute over the debt goes back to 1978 when Keough ordered a Pay-master check-writing machine through Fedoronko, with whom he had dealt Fedoronko and others familiar with the case said.

Fedoronko said he sent bills to Keough in Tehran each month for a year, but never received payment. Several months ago the machine was returned by an Alexandria consulting firm that worked with Keough, but without payment, he said.

"At that point I sued," Fedoronko said. A small claims court justice awarded him the money, but later informed him Keough was a hostage, he said.

"I dropped him from the suit as soon as I heard. Out of 220 million Americans I had to pick on one of those guys. I don't know what I'll do now, it's a very cloudy area whether the school even exists anymore. I'd just like to see the hostages freed," he said.